Transformation of 16-dehydroprogesterone and 17α-hydroxyprogesterone by Mucor piriformis

Mucor piriformis was used to study the mode of transformation of 16-dehydroprogesterone (I, pregna-4, 16-diene-3, 20-dione) and 17-hydroxyprogesterone (II, 17-hydroxypregn-4-ene-3, 20-dione). Biotransformation products formed from I were 14-hydroxypregna-4, 16-diene-3, 20-dione (Ia), 7, 14-dihydroxypregna-4, 16-diene-3, 20-dione (Ib), 3, 7, 14-trihydroxy-5-pregn-16-en-20-one (Ic), and 3, 7, 14-trihydroxy-5-pregn-16-en-20-one (Id). Metabolites Ic and Id appear to be hitherto unknown. Time-course studies suggested that the transformation is initiated by hydroxylation at the 14-position (Ia) followed by hydroxylation at the 7-position (Ib). Microsomes (105,000 g sediment) prepared from 16-dehydroprogesterone-induced cells hydroxylate I to its 14-hydroxy derivative (Ia) in the presence of NADPH. Incubation of Ia with the organism resulted in the formation of Ib, Ic and Id. Biotransformation products formed from compound II were 17, 20-dihydroxypregn-4-en-3-one (IIa), 7, 17-dihydroxypregn-4-ene-3, 20-dione (IIb), 6, 17, 20-trihydroxypregn-4-en-3-one (IIc) and 11, 17, 20-trihydroxypregn-4-en-3-one (IId). Time-course studies indicated that IIa is the initial product formed, which is further hydroxylated either at the 6 or 11 position. Incubation of IIa with the organism resulted in the formation of IIc and IId. Reduction of the 4-en-3-one system and 20-keto group has not been observed before in organisms of the order Mucorales. In addition, M. piriformis has been shown to carry out hydroxylation at the C-6, C-7, C-11 and C-14 positions in the steroid molecules tested.     

Effect of DNA Local Conformation on the Affinity and Binding Specificity of bis-Netropsins to DNA

The interaction of short nucleotide duplexes with bis-netropsins, in which netropsin fragments are linked tail-to-tail via cis-diammineplatinum group (Nt–Pt(NH ₃ )–Nt) or aliphatic pentamethylene chain (Nt–(CH ₂ ) ₅ –Nt), has been studied. Both bis-netropsins have been shown to bind to DNA oligomer 5"-CCTATATCC-3" (I) as a hairpin with parallel orientation of netropsin fragments in 1:1 stoichiometry. Monodentate binding has been detected upon binding of bis-netropsins to other duplexes of sequences 5"-CCXCC-3" [where X = TTATT (II), TTAT (III), TTTTT (IV), and AATTT (V)] along with the binding of bis-netropsins as a hairpin. The formation of dimeric antiparallel motif between the halves of two bound bis-netropsin molecules has been observed in the complexes of Nt–(CH ₂ ) ₅ –Nt with DNA oligomers IV and V. The ratio of binding constant of bis-netropsin as a hairpin ( ₂) to monodentate binding constant ( ₁) has been shown to correlate with the width and/or conformational lability of DNA in the binding site. The share of bis-netropsin bound as a hairpin decreases in the order: TATAT > TTATT > TTAAT > TTTTT > AATTT, whereas the contribution of monodentate binding rises. The minimal strong binding site for Nt–Pt(NH ₃ )–Nt and Nt–(CH ₂ ) ₅ –Nt binding as a hairpin has been found to be DNA duplex 5"-CGTATACG-3".     

Transformation of dehydroepiandrosterone and pregnenolone by Mucor piriformis

The mode of transformation of dehydroepiandrosterone (I, 3-hydroxyandrost-5-en-17-one) and pregnenolone (II, 3-hydroxypregn-5-en-20-one) was studied using Mucor piriformis. Biotransformation products formed from I were 3,17-dihydroxyandrost-5-ene (Ia), 3-hydroxyandrost-5-ene-7,17-dione (Ib), 3,17-dihydroxyandrost-5-en-7-one (Ic), 3,7-dihydroxyandrost-5-en-17-one (Ie). Biotransformation products formed from compound II were 3,7-dihydroxypregn-5-en-20-one (IIa) and 3,7,11-trihydroxypregn-5-en-20-one (IIb). The organism did not carry out isomerization of the 5-en-3-ol to a 4-en-3-one system in the steroid molecules tested. In addition, it failed to carry out 14-hydroxylation possibly because of the lack of a 4-en-3-one system in I and II, and stereospecific hydroxylation at the C-7 position in I and II.     

The Effect of 15-Ketosterol Analogues with a 5,6-Dimethylhept-3-en-2-yl Chain at C17 on Cholesterol Metabolism in Hep G2 Hepatoma Cells

The effect on cholesterol metabolism in Hep G2 hepatoma cells was studied for new analogues of 15-ketosterol [3-hydroxy-5-cholest-8(14)-en-15-one] (I): (24S)-3-hydroxy-24-methyl-5-cholesta-8(14),22-diene-15-one (II), (24S)-3-hydroxy-24-methyl-5-cholesta-8(14),22-diene-15-one (III), and (24S)-24-methyl-5-cholesta-8(14),22-diene-3,15-dione (IV). Analogues (I) and (II) were found to be equally effective inhibitors of cholesterol biosynthesis after a 3-h incubation with Hep G2 cells; however, (II) produced a stronger inhibitory effect after a 24-h incubation or after an incubation of cells preliminarily treated with the inhibitor in a medium containing no ketosterol. The ability of ketosterols to inhibit cholesterol biosynthesis decreased in the order (II) > (IV) > (III). Ketosterol (II) inhibited, whereas ketosterol (III) stimulated the biosynthesis of cholesteryl esters. (IV) stimulated the biosynthesis of cholesteryl esters at a concentration of 1–10 M and exerted no marked effect at a concentration of 30 M. These results indicate that 8(14)-15-ketosterols containing a modified side chain are of interest as regulators of cholesterol metabolism in liver cells.     

Synthesis of Triazole Nucleoside Derivatives

Abstract

5′-O-Mesyl-2′,3′-O-isopropylidene ribonucleosides (4 and 12) were converted to their 5′-substituted nucleosides in good yields by reacted with NaN₃ or KI. 2′,3′-O-Isopropylidene ribonucleosides (3 and 11) were prepared in good yields from ribonucleosides 1 and 2 with a reaction mixture of acetone and triethyl orthoformate instead of using acetone diethyl acetal. Compound 1 or 2 was treated with 2-acetoxyisobutyryl halide (Cl or Br) to give 1-[2-O-acetyl-3-halo-3-deoxy-5-O-(2,5,5-trimethyl-1,3-dioxolan-4-on-2-yl)-β-D-xylofuranosyl]-1,2,4-triazole-3-carboxamide (19, 22, and 23) in high yields. Instead of using 2-acetoxyisobutyryl bromide, the mixture of 2-acetoxyisobutyryl chloride and NaBr was employed in the synthesis of 22 and 23. Treatment of 19 with an activated Zn/Cu couple and deprotection gave 2′,3′-anhydro nucleoside (21), and treatment of 22 and 23 with an activated Zn/Cu couple and a little of HOAc and deprotection gave corresponding 2′,3′-unsaturated triazole nucleosides (24 and 25), respectively. The biological activity of the compounds (7 ～ 10, 15 ～ 18, and 24) was examined in human liver cancer cells (A-549), lung cancer cells (BEL-7402), and Flu-A cells.

Synthesis of Triazole Nucleoside Derivatives

All authors

Zicheng Li, Shuhua Chen, Ning Jiang & Gang Cui

https://doi.org/10.1081/NCN-120022032

Published online:

07 February 2007

Compound 1.     

7.

A dominant mutation (SAD) bypassing the requirement for the a mating type locus in yeast sporulation     

Yona Kassir  Ira Herskowitz 《Molecular & general genetics : MGG》1980,180(2):315-322

Summary SAD (suppressor of a deficiencies) is a mutation that allows -mater diploids such as / or a1^-/ strains to sporulate. This mutation is unstable and reverts to wildtype (sad ⁺) even in strains homozygous for SAD. SAD is dominant to sad ⁺: / and a1^-/ sad ¹/SAD diploids are sporulation-proficient. SAD is located on chromosome III, 40 cM distal to the mating type locus, between THR4 and HMR a. The ability of SAD to support sporulation requires the presence of an mating type locus with an active 2 function. Possible models for the action of SAD are (1) SAD bypasses the need for a1 function in sporulation, and (2) SAD provides a1 function to MAT a1^- mutants by supplying a1 function itself, for example, by allowing expression of a silent copy of MAT a.     

8.

Existe-T-IL des chromosomes sexuels multiples chez le campagnol,Microtus arvalis pallas?     

Robert Matthey 《Genetica》1969,40(1):517-526

The conclusions ofRaicu, Kirillova & Hamar (1969), according to whichMicrotus arvalis has multiple sex chromosomes (X ₁ X ₂ Y ₁ Y ₂, X ₁ X ₁ X ₂ X ₂), are in contradiction to the earlier work ofRenaud (1938) andMatthey (1953) who have reported heterogamety of the XY, XX type for this species as is the situation in the majority of mammals. The mechanism proposed byRaicu and his coauthors in unknown in mammals where only cases of multiple sex-chromosome mechanisms XY ₁ Y ₂, XX and X ₁ X ₂ Y, X ₁ X ₁ X ₂ X ₂ have been described. It was necessary therefore to reexamine the situation in this vole. The author is of the opinion that the conclusions ofRaicu and his coauthors cannot be substantiated and that in this case we have indeed the common type of sex determination.     

9.

The Synthesis of [(β‐d‐Ribofuranosyloxy)‐methyl]nucleosides     

《Nucleosides, nucleotides & nucleic acids》2013,32(4):655-669

     

10.

Microbial transformation of ginsenoside Rb1 by Rhizopus stolonifer and Curvularia lunata   总被引：2，自引：0，他引：2  

Dong A  Ye M  Guo H  Zheng J  Guo D 《Biotechnology letters》2003,25(4):339-344

Of 49 microbial strains screened for their capabilities to transform ginsenoside Rb₁, Rhizopus stolonifer and Curvularia lunata produced four key metabolites: 3-O-[-d-glucopyranosyl-(1,2)--d-glucopyranosyl]- 20-O-[-d-glucopyranosyl]-3,12, 20(S)-trihydroxydammar-24-ene (1), 3-O-[-d-glucopyranosyl-(1,2)--d- glucopyranosyl]-20-O-[-d-glucopyranosyl]-3,12, 20(S)-trihydroxydammar-24-ol (2), 3-O-[-d-gluco- pyranosyl-(1,2)--d-glucopyranosyl]-3, 12, 20(S)-trihydroxydammar-24-ene (3), and 3-O--d-glucopyranosyl-3, 12, 20(S)-trihydroxydammar-24-ene (4), identified by TOF-MS, ¹H- and ¹³C-NMR spectral data. Metabolites 1, 3 and 4 were from the incubation with R. stolonifer, and 1 and 2 from the incubation with C. lunata. Compound 2 was identified as a new compound.     

11.

Synthesis of the disaccharides methyl 4-O-(2′/3′-O-sulfo-β-d-glucopyranosyluronic acid)-2-amino-2-deoxy-α-d-glucopyranoside disodium salts,related to heparin biosynthesis     

Laura Cipolla  Francesco Nicotra  Luigi Lay  Ulf Lindahl  Luigi Panza  Giovanni Russo 《Glycoconjugate journal》1996,13(6):995-1003

The synthesis of the disaccharides methyl 4-O-(2/3-O-sulfo--d-glucopyranosyluronic acid)-2-amino-2-deoxy--d-glucopyranoside3 and4 as, disodium salts is described. Allyl 4,6-O-benzylidene--d-glucopyranoside6 was converted to trichloroacetimidate20 Glycosylation of20 with5 promoted by BF₃·OEt₂ gave disaccharide21. Deacetylation of21 followed by monoacetylation of the resultant diol22 afforded the two monoacetylated disaccharides23 and24. Sulfation and deprotection of each disaccharide gave the desired sulfated compounds3 and4.     

12.

Carbohydrate structural units in glycoproteins and polysaccharides as important ligands for Gal and GalNAc reactive lectins     

Albert M. Wu 《Journal of biomedical science》2003,10(6):676-688

Glycoproteins (gps) contain many carbohydrate epitopes or crypto-glycotopes for Gal and GalNAc reactive lectins. They are present on the cell surface and function as receptors in various life processes. Many exist in soluble or gel form and serve as biological lubricants or as barriers against microbial invasion. During the past two decades, eleven mammalian structural units have been used to express the binding domain of applied lectins. They are:F, GalNAc1 3GalNAc;A, GalNAc1 3Gal;T, Gal1 3GalNAc;I, Gal1 3GlcNAc;II, Gal1 4GlcNAc;B, Gal1 3Gal;E, Gal1 4Gal;L, Gal1 4Glc;P, GalNAc1 3Gal;S, GalNAc1 4Gal andTn, GalNAc1 Ser(Thr). ExceptL andP, all of the units can be found in glycoproteins.Tn, which is an important marker for breast/colon cancer and vaccine development, exists only inO-glycans. NaturalTn gp, the simplest mammalianO-glycan, is exclusively expressed in the armadillo salivary gland. Antifreeze gp is composed of repeating units ofT.Pneumococcus type XIV capsular polysaccharide has uniformII disaccharide as carbohydrate side chains. Asialo human ₁-acid gp and asialo fetuin provide multi-antennaryII structures. Human ovarian cyst gps, which belong to the complex type of glycoform, comprise most of the structural units. To facilitate the selection of lectins that could serve as structural probes, the carbohydrate binding properties of Gal/GalNAc reactive lectins have been classified according to their highest affinity for structural units and their binding profiles are expressed in decreasing order of reactivity. Hence, the binding relationship between glycoproteins and Gal/GalNAc specific lectins can be explored.     

13.

Identification,characterization, and developmental expression of a novel α2 → 8-KDN-transferase which terminates elongation of α2 → 8-linked oligo-polysialic acid chain synthesis in trout egg polysialoglycoproteins     

Takashi Angata  Shinobu Kitazume  Takaho Terada  Ken Kitajima  Sadako Inoue  Frederic A. Troy II  Yasuo Inoue 《Glycoconjugate journal》1994,11(5):493-499

A novel glycosyltransferase which catalyses transfer of deaminated neuraminic acid, KDN (2-keto-3-deoxy-d-glycero-d-galacto-nononic acid) from CMP-KDN to the non-reducing termini of oligo-polysialyl chains of polysialoglycoprotein (PSGP), was discovered in the ovary of rainbow trout (Oncorhynchus mykiss). The KDN-transferase activity was optimal at neutral pH, and stimulated 2 to 2.5-fold by 2–5mm Mg²⁺ or Mn²⁺. Expression of KDN-transferase was developmentally regulated in parallel with expression of the 2 8-polysialytransferase, which catalyses synthesis of the oligo-polysialyl chains in PSGP. Incorporation of the KDN residues into the oligo-polysialyl chains prevented their further elongation, resulting in capping of the oligo-polysialyl chains. This is the first example of a glycosyltransferase that catalyses termination of 2 8-polysialylation in glycoproteins.Abbreviations KDN 2-keto-3-deoxy-d-glycero-d-galacto-nononic acid or naturally occurring deaminated neuraminic acid - Neu5Ac N-acetylneuraminic acid - Neu5Ge N-glycolylneuraminic acid - CMP-KDN cytidine 5-(3-deoxy-d-glycero-d-galacto-2-nonulosonic phosphate) or cytidine 5-KDN phosphate - CMP-NeuAc cytidine 5-Neu5Ac phosphate; oligo-polySia, oligo- and/or polysialic acid - PSGP rainbow trout egg polysialoglycoprotein comprising 2 8-linked oligo- polyNeu5Gc - PSGP (low Sia) a precursor of PSGP present at early stages of oogenesis which contains mostly the disialyl group, Sia2 8Sia2 6- - *K-PSGP [¹⁴C]KDN-labelled PSGP obtained by incubating PSGP and CMP-[¹⁴C]KDN with the immature cortical vesicle fraction P1 containing KDN-transferase - *A-PSGP [¹⁴C]Neu5Ac-labelled PSGP obtained by incubating PSGP and CMP-[¹⁴C]Neu5Ac with the P1 fraction - A-*K-PSGP andK-*K-PSGP the products obtained after incubating *K-PSGP with P1 fraction and unlabelled CMP-Neu5Ac or CMP-KDN, respectively - *K-PSGP _cho ,A-*K-PSGP _cho , andK-*K-PSGP _cho mixture of oligosaccharide alditols obtained by alkaline borohydride treatment of *K-PSGP,A-*K-PSGP, and K-*K-PSGP, respectively - *A-PSGP _cho a mixture of oligosaccharide alditols obtained by alkaline borohydride treatment of [¹⁴C]Neu5Ac-labelled PSGP - Endo-N endo-N-acylneuraminidase - DP degree of polymerization - GLC gas-liquid chromatography - HPLC high performance liquid chromatography - TLC thin layer chromatography     

14.

Acclimation of photosynthesis in Zea mays to low water potentials involves alterations in protoplast volume reduction     

Gerald A. Berkowitz  Kim S. Kroll 《Planta》1988,175(3):374-379

Effects of water-stress treatment of Zea mays L. plants on protoplast volume and photosynthesis in leaf slices exposed to solutions of different osmotic potential ( _s) were studied. Decreased photosynthetic capacity in the leaf slices at low tissue _w was associated with dehydration-induced protoplast-volume reduction. Leaf slices from plants exposed to in-situ water deficits exhibited greater photosynthetic capacity and relative protoplast volume at low water potential ( _w) invitro than tissue from control plants.In-situ water stress induced osmotic adjustment of the leaf tissue as determined by pressure/volume analysis. It is concluded that plant acclimation to low leaf _w may involve a reduced degree of cell shrinkage at a given _w. This acclimation would allow for the maintenance of relatively higher photosynthetic capacity at low water protentials.Symbols _s Osmotic potential - _w water potential New Jersey Agricultural Experiment Station Publication No. 12149-6-87     

15.

Molecular recognition between 4a<Emphasis Type="Italic">S/R</Emphasis>-galanthamine diastereoisomers and α-cyclodextrin     

Sun M  Liu X  Yan L  Luo G  Zhao Y 《Journal of molecular modeling》2003,9(6):419-422

Molecular recognition between 4aS/R-galanthamine diastereoisomers (1: 4aS-galanthamine; 2: 4aR-galanthamine) and -cyclodextrin (-CD) were studied by use of docking and molecular dynamics (MD) simulation approaches. The binding energy of constructed 2···-CD complexes is ~17 kcal mol^–1 lower than that of 1···-CD, implying a stronger binding ability of 2 with -CD than that of 1. The theoretical modeling result is consistent with our previous CZE result, which demonstrated that -CD is an efficient chiral additive for separating 1 and 2. The modeling result also indicates that both hydrophobic interaction and H-bond force may work as major factors for molecular recognition between the galanthamine diastereoisomers and -CD. Figure Chemical structures of 4aS-galanthamine (left) and 4aR-galanthamine (right)Abbreviations Galanthamine 4aS,6R,8aS-4a,5,9,10,11,12-Hexahydroxy-3-methoxy-11-methyl-6H-benzofuro[3a,3,2-e,f]benzazepin-6-ol     

16.

Carbohydrate Structural Units in Glycosphingolipids as Receptors for Gal and GalNAc Reactive Lectins   总被引：3，自引：0，他引：3  

Wu AM 《Neurochemical research》2002,27(7-8):593-600

Glycosphingolipids (GSLs) contain many carbohydrate epitopes or crypto-glycotopes for Gal and GalNAc reactive lectins. Many of them are in the nervous system and function as important receptors in various life processes. During the past two decades, 11 mammalian structural units have been used to express the binding domain of applied lectins. They are: F, GalNAc1 3GalNAc; A, GalNAc1 3Gal; T, Gal1 3GalNAc; I, Gal1 3GlcNAc; II, Gal1 4GlcNAc; B, Gal1 3Gal; E, Gal1 4Gal; L, Gal1 4Glc; P, GalNAc1 3Gal; S, GalNAc1 4Gal, and Tn, GalNAc1 Ser(Thr). Although 10 of them occur in GSLs, only 3 (L , S , and T ) are found in human brain, and 2 (L and II ) are present in the inner structures of human blood group active GSLs. In the families of gangliosides, L and II represent 55% of the total structural units, while the other three units (T , P , and S ) constitute the rest. To facilitate the selection of lectins that could serve as structural probes, the carbohydrate binding specificities of Gal/GalNAc reactive lectins have been classified according to their highest affinity for the structural units and their binding properties expressed by decreasing order of reactivity. Hence, the binding relation between GSLs and Gal/GalNAc specific lectins can be established.     

17.

Lysine Dendrimers and Their Starburst Polymer Derivatives: Possible Application for DNA Compaction and in vitro Delivery of Genetic Constructs     

G. P. Vlasov  V. I. Korol'kov  G. A. Pankova  I. I. Tarasenko  A. N. Baranov  P. B. Glazkov  A. V. Kiselev  O. V. Ostapenko  E. A. Lesina  V. S. Baranov 《Russian Journal of Bioorganic Chemistry》2004,30(1):12-20

We attempted to find some compounds for the effective delivery of gene constructs into cells and obtained two trispherical dendrimers on the basis of lysine, (Lys)₈-(,-Lys)₄-(,-Lys)₂-(,-Lys)-Ala-NH₂ (D1) and ((Lys)₈-(,-Lys)₄-(,-Lys)₂-,-Lys)-Ala-[Lys(Plm)]₂-Ala-NH₂ (D2), as well as the starburst polymeric derivatives of D1, (pVIm) ₈ -D1 and (pLys) _n -D1, containing poly(N-vinylimidazole) and polylysine chains single-point bound to the dendrimer amino groups. The conditions of dendrimer–plasmid DNA complex formation were studied. The intracellular localization of these complexes and the expression of gene constructs delivered with their help were analyzed in transfection experiments on the HeLa cell cultures of human epithelial carcinoma and on mouse C2C12 myoblasts. It was found that the chemical structure of dendrimer D1 and its derivatives significantly affected the structure and properties of complex.     

18.

Metabolic syndrome is associated to high-sensitivity cardiac troponin T elevation     

Assi Milwidsky  Eyal Fisher  Rafael Y. Brzezinski  Michal Ehrenwald  Gabi Shefer  Naftali Stern 《Biomarkers》2019,24(2):153-158

Introduction: Metabolic syndrome (MetS) and high-sensitivity cardiac troponin T (hs-TnT) are associated with higher risk for cardiovascular diseases (CVD). Our aim was to assess the relation between hs-TnT elevation and MetS in a general population sample.

Materials and methods: Individuals participating in an annual health survey program between 2010 and 2016 were included in the study. Blood samples including hs-TnT levels were collected. The study population was divided into three groups based on hs-TnT levels – undetectable (<5?ng/L), intermediate (5–14?ng/L) and elevated (>14?ng/L).

Results: A total of 5994 subjects were included in the study, the mean age was 48.5 and 4336 (72%) were males. Compared with subjects with undetectable hs-TnT the prevalence of MetS was higher in those with detectable and elevated levels – 392 (10%) vs. 270 (15%) and 51 (33%), respectively (p?<?0.001). In a multivariate model adjusted for age, gender and multiple co-morbidities, the number of MetS components and presence of MetS were significantly associated with an increased risk for detectable hs-TnT levels (OR?=?1.02 {for each component}; 95% CI [1.00–1.05], p?=?0.04) and (OR?=?1.13; 95% CI [1.07–1.2], p?<?0.001) respectively. Only the waist, glucose and hypertension components of the MetS were significantly associated with elevated troponin.

Conclusions: The MetS and its distinct components have a cumulative impact on hs-TnT levels in apparently healthy subjects.     

19.

Cannabis 25 1, biotransformation of cannabidiol and cannabidiolic acid by Pinellia ternata tissue segments     

Hiroyuki Tanaka  Ryuji Takahashi  Satoshi Morimoto  Yukihiro Shoyama 《Plant cell reports》1996,15(11):819-823

Two marihuana constituents, cannabidiol (1) and cannabidiolic acid (4) were each converted mainly to two metabolites using tissue segments of Pinellia ternata tuber. The structures of the metabolites formed from 1 were determined to be 1-O-D-glucopyranoside and 1-O-D-diglucopyranoside by ¹H nmr, ¹³C nmr and fabms. Those from 4 were determined as 4-O-D-glucopyranoside and 10-hydroxyl 4-O-D-glucopyranoside. In time course experiments, 1 was absorbed rapidly by the tissues and glucosylated. Hydroxylation subsequent to the glucosylation occurred at the pentyl group in 4.1 For Part 24, see Taura F, Morimoto S, Shoyama Y, Mechoulam R (1995) J Am Chem Soc 117:9766–9767     

20.

Preferred conformations and dynamics of five core structures of mucin typeO-glycans determined by NMR spectroscopy and force field calculations     

Annette Pollex-Krüger  Bernd Meyer  Rainer Stuike-Prill  Volker Sinnwell  Khushi L. Matta  Inka Brockhausen 《Glycoconjugate journal》1993,10(5):365-380

Glycosyltransferases acting onO-glycans have been shown to exhibit distinct specificity for the carbohydrate and the peptide moiety of their substrates. As an approach to study the 3-dimensional interactions between enzymes andO-glycan substrates, we determined the preferred conformations of five oligosaccharide-core structures of mucin type glycoproteins by NMR spectroscopy and by static and dynamic force field calculations. Seven oligosaccharides, representing five basic core structures, were investigated: Gal(1–3)GalNAcBzl (1, core 1), GlcNAc(1–6)[Gal(1–3)]GalNAcBzl (2, core 2), GlcNAc(1–3)GalNacBzl (3, core 3), GlcNAc(1–6)[GlcNAc(1–3)]GalNAcBzl (4, core 4), GlcNAc(1–6)GalNAcBzl (5, core 6), the elongated core 2, Gal(1–4)GlcNAc(1–6)[Gal(1–3)]GalNAcpNp (6) and GalNAc-Bzl (7). The dynamic behaviour of the molecules was studied by Metropolis Monte Carlo (MMC) simulations. Experimental coupling constants, chemical shift changes, and NOEs were compared with results from static energy minimizations and dynamic MMC simulations and show a good agreement. MMC simulations show that the (1–6) linkage is much more flexible than the (1–3) or the (1–4) linkages. The preferred conformations of the disaccharides (1) and (3) show only slight differences due to the additionalN-acetyl group in (3). The conformational equilibrium of (1–3) glycosidic bonds of1 and3 was not affected by attaching a (1–6) linked GlcNAc unit to the GalNAc residue in2 and4. However, experimental and theoretical data show that the (1–6) linkages of the trisaccharides2 and4, which carry an additional (1–3) linked glycosyl residue, change their preferred conformations when compared with (5). The 6-branch also shows significant interactions with the benzyl aglycon altering the preferred conformation of the hydroxymethyl group of the GalNAc to a higher proportion of the gt conformer. The (1–6) linkage of2, 4, and6 can have two different families of conformations of which the lower energy state is populated only to about 20% of the time whereas the other state with a relative enthalpy of 4 kcal mol^–1 is populated to 80%. This fact demonstrates that the two conformational states have different entropy contents. Entropy is implicitly included in MMC simulations but cannot be derived from energy minimizations.Abbreviations Bzl benzyl - COSY correlation spectroscopy - Gal d-galactose - GalNAc N-acetyl-d-galactosamine - GalNAc-ol N-acetylgalactosaminitol - GlcNAc N-acetyl-d-glucosamine - HOHAHA homonuclear Hartmann-Hahn-spectroscopy - MMC metropolis Monte Carlo - NOE nuclear Overhauser enhancement - pNp p-nitrophenyl - ROESY rotating frame Overhauser enhancement spectroscopy - TOCSY totally correlated spectroscopy     

A dominant mutation (SAD) bypassing the requirement for the a mating type locus in yeast sporulation

Summary SAD (suppressor of a deficiencies) is a mutation that allows -mater diploids such as / or a1^-/ strains to sporulate. This mutation is unstable and reverts to wildtype (sad ⁺) even in strains homozygous for SAD. SAD is dominant to sad ⁺: / and a1^-/ sad ¹/SAD diploids are sporulation-proficient. SAD is located on chromosome III, 40 cM distal to the mating type locus, between THR4 and HMR a. The ability of SAD to support sporulation requires the presence of an mating type locus with an active 2 function. Possible models for the action of SAD are (1) SAD bypasses the need for a1 function in sporulation, and (2) SAD provides a1 function to MAT a1^- mutants by supplying a1 function itself, for example, by allowing expression of a silent copy of MAT a.     

Existe-T-IL des chromosomes sexuels multiples chez le campagnol,Microtus arvalis pallas?

The conclusions ofRaicu, Kirillova & Hamar (1969), according to whichMicrotus arvalis has multiple sex chromosomes (X ₁ X ₂ Y ₁ Y ₂, X ₁ X ₁ X ₂ X ₂), are in contradiction to the earlier work ofRenaud (1938) andMatthey (1953) who have reported heterogamety of the XY, XX type for this species as is the situation in the majority of mammals. The mechanism proposed byRaicu and his coauthors in unknown in mammals where only cases of multiple sex-chromosome mechanisms XY ₁ Y ₂, XX and X ₁ X ₂ Y, X ₁ X ₁ X ₂ X ₂ have been described. It was necessary therefore to reexamine the situation in this vole. The author is of the opinion that the conclusions ofRaicu and his coauthors cannot be substantiated and that in this case we have indeed the common type of sex determination.     

Microbial transformation of ginsenoside Rb1 by Rhizopus stolonifer and Curvularia lunata

Of 49 microbial strains screened for their capabilities to transform ginsenoside Rb₁, Rhizopus stolonifer and Curvularia lunata produced four key metabolites: 3-O-[-d-glucopyranosyl-(1,2)--d-glucopyranosyl]- 20-O-[-d-glucopyranosyl]-3,12, 20(S)-trihydroxydammar-24-ene (1), 3-O-[-d-glucopyranosyl-(1,2)--d- glucopyranosyl]-20-O-[-d-glucopyranosyl]-3,12, 20(S)-trihydroxydammar-24-ol (2), 3-O-[-d-gluco- pyranosyl-(1,2)--d-glucopyranosyl]-3, 12, 20(S)-trihydroxydammar-24-ene (3), and 3-O--d-glucopyranosyl-3, 12, 20(S)-trihydroxydammar-24-ene (4), identified by TOF-MS, ¹H- and ¹³C-NMR spectral data. Metabolites 1, 3 and 4 were from the incubation with R. stolonifer, and 1 and 2 from the incubation with C. lunata. Compound 2 was identified as a new compound.     

Synthesis of the disaccharides methyl 4-O-(2′/3′-O-sulfo-β-d-glucopyranosyluronic acid)-2-amino-2-deoxy-α-d-glucopyranoside disodium salts,related to heparin biosynthesis

The synthesis of the disaccharides methyl 4-O-(2/3-O-sulfo--d-glucopyranosyluronic acid)-2-amino-2-deoxy--d-glucopyranoside3 and4 as, disodium salts is described. Allyl 4,6-O-benzylidene--d-glucopyranoside6 was converted to trichloroacetimidate20 Glycosylation of20 with5 promoted by BF₃·OEt₂ gave disaccharide21. Deacetylation of21 followed by monoacetylation of the resultant diol22 afforded the two monoacetylated disaccharides23 and24. Sulfation and deprotection of each disaccharide gave the desired sulfated compounds3 and4.     

Carbohydrate structural units in glycoproteins and polysaccharides as important ligands for Gal and GalNAc reactive lectins

Glycoproteins (gps) contain many carbohydrate epitopes or crypto-glycotopes for Gal and GalNAc reactive lectins. They are present on the cell surface and function as receptors in various life processes. Many exist in soluble or gel form and serve as biological lubricants or as barriers against microbial invasion. During the past two decades, eleven mammalian structural units have been used to express the binding domain of applied lectins. They are:F, GalNAc1 3GalNAc;A, GalNAc1 3Gal;T, Gal1 3GalNAc;I, Gal1 3GlcNAc;II, Gal1 4GlcNAc;B, Gal1 3Gal;E, Gal1 4Gal;L, Gal1 4Glc;P, GalNAc1 3Gal;S, GalNAc1 4Gal andTn, GalNAc1 Ser(Thr). ExceptL andP, all of the units can be found in glycoproteins.Tn, which is an important marker for breast/colon cancer and vaccine development, exists only inO-glycans. NaturalTn gp, the simplest mammalianO-glycan, is exclusively expressed in the armadillo salivary gland. Antifreeze gp is composed of repeating units ofT.Pneumococcus type XIV capsular polysaccharide has uniformII disaccharide as carbohydrate side chains. Asialo human ₁-acid gp and asialo fetuin provide multi-antennaryII structures. Human ovarian cyst gps, which belong to the complex type of glycoform, comprise most of the structural units. To facilitate the selection of lectins that could serve as structural probes, the carbohydrate binding properties of Gal/GalNAc reactive lectins have been classified according to their highest affinity for structural units and their binding profiles are expressed in decreasing order of reactivity. Hence, the binding relationship between glycoproteins and Gal/GalNAc specific lectins can be explored.     

Identification,characterization, and developmental expression of a novel α2 → 8-KDN-transferase which terminates elongation of α2 → 8-linked oligo-polysialic acid chain synthesis in trout egg polysialoglycoproteins

A novel glycosyltransferase which catalyses transfer of deaminated neuraminic acid, KDN (2-keto-3-deoxy-d-glycero-d-galacto-nononic acid) from CMP-KDN to the non-reducing termini of oligo-polysialyl chains of polysialoglycoprotein (PSGP), was discovered in the ovary of rainbow trout (Oncorhynchus mykiss). The KDN-transferase activity was optimal at neutral pH, and stimulated 2 to 2.5-fold by 2–5mm Mg²⁺ or Mn²⁺. Expression of KDN-transferase was developmentally regulated in parallel with expression of the 2 8-polysialytransferase, which catalyses synthesis of the oligo-polysialyl chains in PSGP. Incorporation of the KDN residues into the oligo-polysialyl chains prevented their further elongation, resulting in capping of the oligo-polysialyl chains. This is the first example of a glycosyltransferase that catalyses termination of 2 8-polysialylation in glycoproteins.Abbreviations KDN 2-keto-3-deoxy-d-glycero-d-galacto-nononic acid or naturally occurring deaminated neuraminic acid - Neu5Ac N-acetylneuraminic acid - Neu5Ge N-glycolylneuraminic acid - CMP-KDN cytidine 5-(3-deoxy-d-glycero-d-galacto-2-nonulosonic phosphate) or cytidine 5-KDN phosphate - CMP-NeuAc cytidine 5-Neu5Ac phosphate; oligo-polySia, oligo- and/or polysialic acid - PSGP rainbow trout egg polysialoglycoprotein comprising 2 8-linked oligo- polyNeu5Gc - PSGP (low Sia) a precursor of PSGP present at early stages of oogenesis which contains mostly the disialyl group, Sia2 8Sia2 6- - *K-PSGP [¹⁴C]KDN-labelled PSGP obtained by incubating PSGP and CMP-[¹⁴C]KDN with the immature cortical vesicle fraction P1 containing KDN-transferase - *A-PSGP [¹⁴C]Neu5Ac-labelled PSGP obtained by incubating PSGP and CMP-[¹⁴C]Neu5Ac with the P1 fraction - A-*K-PSGP andK-*K-PSGP the products obtained after incubating *K-PSGP with P1 fraction and unlabelled CMP-Neu5Ac or CMP-KDN, respectively - *K-PSGP _cho ,A-*K-PSGP _cho , andK-*K-PSGP _cho mixture of oligosaccharide alditols obtained by alkaline borohydride treatment of *K-PSGP,A-*K-PSGP, and K-*K-PSGP, respectively - *A-PSGP _cho a mixture of oligosaccharide alditols obtained by alkaline borohydride treatment of [¹⁴C]Neu5Ac-labelled PSGP - Endo-N endo-N-acylneuraminidase - DP degree of polymerization - GLC gas-liquid chromatography - HPLC high performance liquid chromatography - TLC thin layer chromatography     

Acclimation of photosynthesis in Zea mays to low water potentials involves alterations in protoplast volume reduction

Effects of water-stress treatment of Zea mays L. plants on protoplast volume and photosynthesis in leaf slices exposed to solutions of different osmotic potential ( _s) were studied. Decreased photosynthetic capacity in the leaf slices at low tissue _w was associated with dehydration-induced protoplast-volume reduction. Leaf slices from plants exposed to in-situ water deficits exhibited greater photosynthetic capacity and relative protoplast volume at low water potential ( _w) invitro than tissue from control plants.In-situ water stress induced osmotic adjustment of the leaf tissue as determined by pressure/volume analysis. It is concluded that plant acclimation to low leaf _w may involve a reduced degree of cell shrinkage at a given _w. This acclimation would allow for the maintenance of relatively higher photosynthetic capacity at low water protentials.Symbols _s Osmotic potential - _w water potential New Jersey Agricultural Experiment Station Publication No. 12149-6-87     

Molecular recognition between 4a<Emphasis Type="Italic">S/R</Emphasis>-galanthamine diastereoisomers and α-cyclodextrin

Molecular recognition between 4aS/R-galanthamine diastereoisomers (1: 4aS-galanthamine; 2: 4aR-galanthamine) and -cyclodextrin (-CD) were studied by use of docking and molecular dynamics (MD) simulation approaches. The binding energy of constructed 2···-CD complexes is ~17 kcal mol^–1 lower than that of 1···-CD, implying a stronger binding ability of 2 with -CD than that of 1. The theoretical modeling result is consistent with our previous CZE result, which demonstrated that -CD is an efficient chiral additive for separating 1 and 2. The modeling result also indicates that both hydrophobic interaction and H-bond force may work as major factors for molecular recognition between the galanthamine diastereoisomers and -CD. Figure Chemical structures of 4aS-galanthamine (left) and 4aR-galanthamine (right)Abbreviations Galanthamine 4aS,6R,8aS-4a,5,9,10,11,12-Hexahydroxy-3-methoxy-11-methyl-6H-benzofuro[3a,3,2-e,f]benzazepin-6-ol     

Carbohydrate Structural Units in Glycosphingolipids as Receptors for Gal and GalNAc Reactive Lectins

Glycosphingolipids (GSLs) contain many carbohydrate epitopes or crypto-glycotopes for Gal and GalNAc reactive lectins. Many of them are in the nervous system and function as important receptors in various life processes. During the past two decades, 11 mammalian structural units have been used to express the binding domain of applied lectins. They are: F, GalNAc1 3GalNAc; A, GalNAc1 3Gal; T, Gal1 3GalNAc; I, Gal1 3GlcNAc; II, Gal1 4GlcNAc; B, Gal1 3Gal; E, Gal1 4Gal; L, Gal1 4Glc; P, GalNAc1 3Gal; S, GalNAc1 4Gal, and Tn, GalNAc1 Ser(Thr). Although 10 of them occur in GSLs, only 3 (L , S , and T ) are found in human brain, and 2 (L and II ) are present in the inner structures of human blood group active GSLs. In the families of gangliosides, L and II represent 55% of the total structural units, while the other three units (T , P , and S ) constitute the rest. To facilitate the selection of lectins that could serve as structural probes, the carbohydrate binding specificities of Gal/GalNAc reactive lectins have been classified according to their highest affinity for the structural units and their binding properties expressed by decreasing order of reactivity. Hence, the binding relation between GSLs and Gal/GalNAc specific lectins can be established.     

Lysine Dendrimers and Their Starburst Polymer Derivatives: Possible Application for DNA Compaction and in vitro Delivery of Genetic Constructs

We attempted to find some compounds for the effective delivery of gene constructs into cells and obtained two trispherical dendrimers on the basis of lysine, (Lys)₈-(,-Lys)₄-(,-Lys)₂-(,-Lys)-Ala-NH₂ (D1) and ((Lys)₈-(,-Lys)₄-(,-Lys)₂-,-Lys)-Ala-[Lys(Plm)]₂-Ala-NH₂ (D2), as well as the starburst polymeric derivatives of D1, (pVIm) ₈ -D1 and (pLys) _n -D1, containing poly(N-vinylimidazole) and polylysine chains single-point bound to the dendrimer amino groups. The conditions of dendrimer–plasmid DNA complex formation were studied. The intracellular localization of these complexes and the expression of gene constructs delivered with their help were analyzed in transfection experiments on the HeLa cell cultures of human epithelial carcinoma and on mouse C2C12 myoblasts. It was found that the chemical structure of dendrimer D1 and its derivatives significantly affected the structure and properties of complex.     

Metabolic syndrome is associated to high-sensitivity cardiac troponin T elevation

Introduction: Metabolic syndrome (MetS) and high-sensitivity cardiac troponin T (hs-TnT) are associated with higher risk for cardiovascular diseases (CVD). Our aim was to assess the relation between hs-TnT elevation and MetS in a general population sample.

Materials and methods: Individuals participating in an annual health survey program between 2010 and 2016 were included in the study. Blood samples including hs-TnT levels were collected. The study population was divided into three groups based on hs-TnT levels – undetectable (<5?ng/L), intermediate (5–14?ng/L) and elevated (>14?ng/L).

Results: A total of 5994 subjects were included in the study, the mean age was 48.5 and 4336 (72%) were males. Compared with subjects with undetectable hs-TnT the prevalence of MetS was higher in those with detectable and elevated levels – 392 (10%) vs. 270 (15%) and 51 (33%), respectively (p?<?0.001). In a multivariate model adjusted for age, gender and multiple co-morbidities, the number of MetS components and presence of MetS were significantly associated with an increased risk for detectable hs-TnT levels (OR?=?1.02 {for each component}; 95% CI [1.00–1.05], p?=?0.04) and (OR?=?1.13; 95% CI [1.07–1.2], p?<?0.001) respectively. Only the waist, glucose and hypertension components of the MetS were significantly associated with elevated troponin.

Conclusions: The MetS and its distinct components have a cumulative impact on hs-TnT levels in apparently healthy subjects.     

Cannabis 25 1, biotransformation of cannabidiol and cannabidiolic acid by Pinellia ternata tissue segments

Two marihuana constituents, cannabidiol (1) and cannabidiolic acid (4) were each converted mainly to two metabolites using tissue segments of Pinellia ternata tuber. The structures of the metabolites formed from 1 were determined to be 1-O-D-glucopyranoside and 1-O-D-diglucopyranoside by ¹H nmr, ¹³C nmr and fabms. Those from 4 were determined as 4-O-D-glucopyranoside and 10-hydroxyl 4-O-D-glucopyranoside. In time course experiments, 1 was absorbed rapidly by the tissues and glucosylated. Hydroxylation subsequent to the glucosylation occurred at the pentyl group in 4.1 For Part 24, see Taura F, Morimoto S, Shoyama Y, Mechoulam R (1995) J Am Chem Soc 117:9766–9767     

Preferred conformations and dynamics of five core structures of mucin typeO-glycans determined by NMR spectroscopy and force field calculations

Glycosyltransferases acting onO-glycans have been shown to exhibit distinct specificity for the carbohydrate and the peptide moiety of their substrates. As an approach to study the 3-dimensional interactions between enzymes andO-glycan substrates, we determined the preferred conformations of five oligosaccharide-core structures of mucin type glycoproteins by NMR spectroscopy and by static and dynamic force field calculations. Seven oligosaccharides, representing five basic core structures, were investigated: Gal(1–3)GalNAcBzl (1, core 1), GlcNAc(1–6)[Gal(1–3)]GalNAcBzl (2, core 2), GlcNAc(1–3)GalNacBzl (3, core 3), GlcNAc(1–6)[GlcNAc(1–3)]GalNAcBzl (4, core 4), GlcNAc(1–6)GalNAcBzl (5, core 6), the elongated core 2, Gal(1–4)GlcNAc(1–6)[Gal(1–3)]GalNAcpNp (6) and GalNAc-Bzl (7). The dynamic behaviour of the molecules was studied by Metropolis Monte Carlo (MMC) simulations. Experimental coupling constants, chemical shift changes, and NOEs were compared with results from static energy minimizations and dynamic MMC simulations and show a good agreement. MMC simulations show that the (1–6) linkage is much more flexible than the (1–3) or the (1–4) linkages. The preferred conformations of the disaccharides (1) and (3) show only slight differences due to the additionalN-acetyl group in (3). The conformational equilibrium of (1–3) glycosidic bonds of1 and3 was not affected by attaching a (1–6) linked GlcNAc unit to the GalNAc residue in2 and4. However, experimental and theoretical data show that the (1–6) linkages of the trisaccharides2 and4, which carry an additional (1–3) linked glycosyl residue, change their preferred conformations when compared with (5). The 6-branch also shows significant interactions with the benzyl aglycon altering the preferred conformation of the hydroxymethyl group of the GalNAc to a higher proportion of the gt conformer. The (1–6) linkage of2, 4, and6 can have two different families of conformations of which the lower energy state is populated only to about 20% of the time whereas the other state with a relative enthalpy of 4 kcal mol^–1 is populated to 80%. This fact demonstrates that the two conformational states have different entropy contents. Entropy is implicitly included in MMC simulations but cannot be derived from energy minimizations.Abbreviations Bzl benzyl - COSY correlation spectroscopy - Gal d-galactose - GalNAc N-acetyl-d-galactosamine - GalNAc-ol N-acetylgalactosaminitol - GlcNAc N-acetyl-d-glucosamine - HOHAHA homonuclear Hartmann-Hahn-spectroscopy - MMC metropolis Monte Carlo - NOE nuclear Overhauser enhancement - pNp p-nitrophenyl - ROESY rotating frame Overhauser enhancement spectroscopy - TOCSY totally correlated spectroscopy