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1.
The rate of CO2- and p-benzoquione-dependent photosynthetic O2 evolution by Anabaena variabilis cells remained unaltered and the rate of O2 uptake observed after switching off the light (endogenous respiration) was enhanced by a factor of 6–8 when the O2 concentration was increased from 200 to 400 M. Photosystem-I-linked O2 uptake and respiration of the cells incubated with ascorbate and N,N,NN-tetramethyl-p-phenylenediamine was not appreciable influenced by the O2 concentration. 2-Iodo-6-isopropyl-3-methyl-2,4,4-trinitrodiphenyl ether, blocking electron transfer at the plastoquinone level, suppressed O2 evolution and had no influence on endogenous respiration. 2-n-Heptyl-4-hydroxyquinoline-N-oxide, an inhibitor of electron transfer between photosystems II and I, as well as the cytochrome-oxidase inhibitors N
3
-
, CN- and NH2OH, caused a 35–50% retardation of endogenous respiration and blocked photosynthetic O2 evolution. The molar ratio of cytochromes b6, f, c-553, aa3 and photosystem-I reaction centers in the isolated membranes equalled approx. 2:1:2:0.7:2. It is inferred that endogenous respiration of A. variabilis cells is inhibited by the light-induced electron flow through both photosystems at the level of the plastoquinone-plastocyanin-oxidoreductase complex.Abbreviations DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- DNP-INT
2-iodo-6-isopropyl-3-methyl-2,4,4-trinitrodiphenyl ether
- Hepes
4-(2-hydroxyethyl)-1-piperazine ethansulfonic acid
- TMPD
N,N,NN-tetramethyl-p-phenylenediamine 相似文献
2.
Teruo Yoshino Minobu Sadamitsu Megumi Minagawa Gerd Reuter Roland Schauer 《Glycoconjugate journal》1988,5(4):377-384
The preparation of benzyl 2,3,6,2,6-penta-O-benzyl--d-lactoside, which is a key intermediate for chemical synthesis of oligosaccharide components of glycosphingolipids, was achieved by an improved method. The 3-O-p-methoxybenzyl and 3-O-methyl derivatives were prepared from benzyl 2,3,6,2,6-penta-O-benzyl--d-lactoside through stannylation. By using benzyl -d-lactoside as starting material, benzyl 3-O-methyl-, 3-O-benzyl- and 3-O-p-methoxybenzyl--d-lactoside were regioselectively synthesized using the same procedure. 相似文献
3.
Irene M.A. Nooren Ke-Yu Wang Philip N. Borer István Pelczer 《Journal of biomolecular NMR》1998,11(3):319-328
The subject RNA models the binding site for the coat protein of the R17 virus, as well as the ribosome recognition sequence for the R17 replicase gene. With an RNA of this size, overlaps among the sugar protons complicate assignments of the 1H NMR spectrum. The cross peaks that overlap significantly in 2D-NOE spectra can frequently be resolved by introducing a third, in our approach the double-quantum, frequency axis. In particular the planes in a 3D-NOE/2QC spectrum perpendicular to the 2Q axis are extremely useful, showing a highly informative repeating NOE-2Q pattern. In this experiment substantial J-coupling confers special advantages. This always occurs for geminal pairs (H5/H5 for RNA plus H2/H2 for DNA), as well as for H5/H6, for H3/H4 in sugars with substantial populations of the N-pucker, for H1/H2 for S-puckered sugars, and usually for H2/H3. For the 24-mer RNA hairpin the additional information from the 3D-NOE/2QC spectrum allowed assignment of all of the non-exchangeable protons, eliminating the need for stable-isotope labeling. 相似文献
4.
2D NMR spectroscopy and J coupling constant analysis are applied to resolve the structure of two photoproducts of thymidylyl-(35)-thymidine. These products are cyclobutane type thymine dimers possessing the cis-syn (the predominant one) and trans-syn geometry. The cis-syn is formed in an ANTI-ANTI conformation about the N-glycosyl linkages and resembles the normal base-stacked configuration. The glycosidic conformation in solution of the 5 terminal fragment differs from the crystal in which the less common SYN conformation is observed. In this isomer only the sugar pucker of the 3 terminal fragment is changed substantially with respect to the dinucleotide. The trans-syn isomer is formed in a SYN-ANTI glycosidic conformation. In this isomer the sugar puckers of both deoxyribose rings are affected and a preference for a pure 2-endo conformation is observed.Abbreviations dTpdT
2-deoxythymidylyl-(35)-2-deoxythymidine
- dTp[]dT
cyclobutane type photodimers of dTpdT
- dTp- and dTp[]-
their 5' terminal fragments (fragment A)
- -pdT and-[]pdT
their 3 terminal fragments (fragment B)
- RP-HPLC
reversed-phase high-performance liquid chromatography
- COSY
two-dimensional correlated spectroscopy
- 2D NOE
two-dimensional nuclear Overhauser spectroscopy 相似文献
5.
Summary Soluble lead salts and a number of lead-containing minerals catalyze the formation of oligonucleotides from nucleoside 5-phosphorimidazolides. The effectiveness of lead compounds correlates strongly with their solubility. Under optimal conditions we were able to obtain 18% of pentamer and higher oligomers from ImpA. Reactions involving ImpU gave smaller yields.Abbreviations A
adenosine
-
U
uridine
-
Im
imidazole
-
MeIm
1-methyl-imidazole
-
EDTA
ethylenediaminetetraacetic acid
-
pA
adenosine 5-phosphate
-
pU
uridine 5-phosphate
-
Ap
adenosine cyclic 2:3-phosphate
-
ATP
adenosine 5-triphosphate
-
AppA
P1,P2-diadenosine 5-diphosphate
-
pNp (N = A,U)
nucleotide 2(3), 5-diphosphate
-
ImpA
adenosine 5-phosphoreimidazolide
-
ImpU
uridine 5-phosphorimidazolide
-
A
2pA
adenylyl-[25]-adenosine
-
A
3pA
adenylyl-[35]-adenosine
-
pA
2pA
5-phospho-adenylyl-[25]-adenosine
-
pA
3pA
5-phospho-adenylyl-[35]-adenosine
-
pUpU
5-phospho-uridylyl-uridine
-
pApU
5-phospho-adenylyl-uridine
-
pUpA
5-phospho-uridylyladenine
-
(pA)n (n, 2,3,4,)
oligoadenylates with 5 terminal phosphate
-
ImpApA
5-phosphorimidazolide of adenylyl adenosine
-
(pA)
5+
pentamer and higher oligoadenylates with 5 terminal phosphate
-
(Ap)nA (n = 2,3,4)
oligoadenylates without terminal phosphates
In the following we do not specify the nature of the internucleotide linkageIn the following we do not specify the nature of the internucleotide linkage 相似文献
6.
Summary Evaporation of a solution of thymidine plus either theexo or theendo diastereomer of uridine cyclic 2,3-O, O-phosphorothioate (U > p(S) in 1,2-diaminoethane hydrochloride buffer gave the 2,5 and 3,5 isomers of (P-thio) uridylylthymidine (Up(S)dT) in a ratio of 1:2 with a combined yield of about 20%. These isomers were re-converted to U > p(S) and dT by a reaction that is known to proceed by an in-line mechanism. Both the 2,5 and 3,5 isomers gave as product the same diastereomer of U > p(S) that had been used originally in their formation. These dry-state prebiotic reactions (Verlander, Lohrmann, and Orgel 1973) are thus shown to be stereospecific, and both the 2,5 and 3,5 internucleotide bonds are formed by an in-line mechanism.Abbreviations DAE
1,2-diaminoethane
- HPLC
high pressure liquid chromatography
- RNase
bovine pancreatic ribonuclease A, EC 3.1.4.22
- TEAB
triethylammonium bicarbonate
- tris
tris(hydroxymethyl)aminomethane
- UMP(S)
uridine monophosphorothioate
- U > p
uridine cyclic 2,3-phosphate
- U > p(S)
uridine cyclic 2,3-O, O-phosphorothioate
- Up(S)dT
(P-thio)uridylylthymidine
- U2p(Rp-S)5dT
(P-thio)uridylylthymidine with theR configuration at phosphorous, and a 2,5 internucleotide linkage 相似文献
7.
An aerobic bacterial strain, designated R04, belonging to the genus Rhodococcus has been isolated and characerized by 16S rDNA analysis. The capability of this strain to degrade seven different polychlorinated biphenyls (CBs), 500 ppm 3-CB, 3,4-CB, 4,4-CB, 2,4,6-CB, 2,4,5-CB, 2,3,4,5-CB and 3,4,3,4-CB in liquid medium, was evaluated. After 5 days of incubation, the concentration of chloride increased to 0.35 mM in cultures containing 3-CB and R04, whereas in cultures with 3,4-CB, 2,3,4,5-CB or 3,4,3,4-CB plus R04 the chloride content increased to 0.1 mM. However, non-stoichiometric amounts of chloride were produced in cultures with R04 and 4,4-CB, 2,4,6-CB and 2,4,5-CB. The spectrum of supernatants from R04 grown on seven PCBs had a UV-visible (UV-VIS) absorption at 200–500 nm, characteristic of biphenyl-derived cleavage products. Gas-chromatographic (GC) analysis showed that R04 was able to transform 100% of 3-CB and 3,4-CB after 1 day of incubation, and 95% of 4,4-CB, 2,4,6-CB, 2,4,5-CB, 2,3,4,5-CB and 3,4,3,4-CB after 5 days of incubation. The position of the chlorine substituents on the rings strongly influenced the degradation of polychlorinated biphenyls (PCBs) and their intermediate metabolites by Rhodococcus sp. R04. The degradation of PCBs was further evaluated by monitoring intermediate metabolites of PCBs. 相似文献
8.
As a precursor for the chemical synthesis of sialylated oligosaccharides, the trisaccharide glycoside Neu5Ac (2-8)Gal(1-4)GlcNAc(1-O)-pent-4-ene was synthesized starting from GlcNAc(1-O)-pent-4-ene, UDP-glucose andN-acetylneuraminic acid in a one pot reaction employing galactosyltransferase and (2-6)sialyl-transferase in a complete cofactor regeneration system.Abbreviations Neu5Ac
N-acetylneuraminic acid
- CMP-Neu5Ac
cytidine 5-monophosphosialate
- CMP
cytidine 5-monophosphate
- CDP
cytidine 5-diphosphate
- CTP
cytidine 5-triphosphate
- Gal
galactose
- GlcNAc
N-acetylglucosamine
- UDP
uridine 5-diphosphate
- UDP-Glc
uridine-5-diphosphoglucose
- UDP-Gal
uridine-5-diphosphogalactose
- PEP
phosphoenolpyruvate 相似文献
9.
Summary
N, N-Ethylene-bridged bis-(S)-methionine[(2S, 7S)-2, 7-bis(2-methyl-thioethyl)-3,6-diazaoctanedioic acid] derived from (S)-methionine and 1,2-dibromoethane was cyclized and esterified simultaneously in boiling ethanol in the presence of an appropriate amount of strong acid such asp-toluenesulfonic acid, affording a cyclic compound,N, N-ethylene-bridged (S)-methionyl-(S)-methionine ethyl ester {ethyl(2S, 3S)-4-(methylthio)-2-[2-oxo-3-(2-methylthioethyl)-1-piperazinyl] butanoate}, exclusively in 80–90% yields. It was also found that, by applying this method, 70–80% yields of the otherN, N-ethylenebridged dipeptides containing (S)-tryptophan, -tyrosine and -N()-benzyloxycarbonyllysine were obtained. 相似文献
10.
Six water bodies in the region of Kangerlussuaq, West Greenland (67° 30 N, 50° 46 W), and four near Ammassalik, East Greenland (65° 36 N, 37° 38 W) were sampled. Sixty-nine taxa (2 Bdelloidea, 67 Monogononta) are reported, forty-six of which represent new records for Greenland. Proales pejleri n. sp. is described. 相似文献
11.
Kojima C Kawashima E Sekine T Ishido Y Ono A Kainosho M Kyogoku Y 《Journal of biomolecular NMR》2001,19(1):19-31
The sugar conformation of a DNA decamer was studied with proton-proton 3J coupling constants. Two samples, one comprising stereospecifically labeled 2-R-2H for all residues and the other 2-S-2H, were prepared by the method of Kawashima et al. [J. Org. Chem. (1995) 60, 6980–6986; Nucleosides Nucleotides (1995) 14, 333–336], the deuterium labeling being highly stereospecific 99% for all 2-2H, 98% for 2-2H of A, C, and T, and 93% for 2-2H of G). The 3J values of all H1-H2 and H1-H2 pairs, and several H2-H3 and H2-H3 pairs were determined by line fitting of 1D spectra with 0.1–0.2 Hz precision. The observed J coupling constants were explained by the rigid sugar conformation model, and the sugar conformations were found to be between C3-exo and C2-endo with m values of 26° to 44°, except for the second and 3 terminal residues C2 and C10. For the C2 and C10 residues, the lower fraction of S-type conformation was estimated from JH1H2 and JH1H2 values. For C10, the N–S two-site jump model or Gaussian distribution of the torsion angle model could explain the observed J values, and 68% S-type conformation or C1-exo conformation with 27° distribution was obtained, respectively. The differences between these two motional models are discussed based on a simple simulation of J-coupling constants. 相似文献
12.
Andrea E. Lucchini Teresita A. Lisa Carlos E. Domenech 《Archives of microbiology》1990,153(6):596-599
In Pseudomonas aeruginosa and Rhizobium meliloti several choline derivatives, utilized as the sole carbon and nitrogen source, increase acid phosphatase activity. The enzyme activity of both bacteria could be released into the surrounding medium by EDTA-lysozyme treatment. The R. meliloti acid phosphatase activity of crude periplasmic extracts measured with p-nitrophenylphosphate was not inhibited by the presence of 5 mM choline, betaine, trimethylammonium or phosphorylcholine. The activity could not be detected using phosphorylethanolamine or phosphorylcholine as substrates. Among several phosphoesters tested only pyridoxal-5-phosphate was hydrolyzed at a considerable rate. In 7.5% polyacrylamide slab gel electrophoresis (non-denaturing conditions) of crude extracts obtained from bacteria grown in the presence of serine, glutamate, aspartate or dimethylglycine a phosphatase activity with identical mobility could be detected when alpha-naphthylphosphate or pyridoxal-5-phosphate were used as substrates. In conclusion, although the coline metabolites are capable of increasing acid phosphatase activities in R. meliloti and in P. aeruginosa, there are two different enzymes involved, apparently in different metabolisms.Abbreviations p-NPP
p-nitrophenyl phosphate
- PLP
pyridoxal-5-phosphate
- PMP
pyridoxamine-5-phosphate
Recipient of a Fellowship from the CONICORMember of the SAPIU-CONICETCareer Member of the CONICET 相似文献
13.
In the present paper we describe the synthesis of Sepharose-boundN-(5-phosphopyridoxyl)-amino-oxyacetic acid,N-(5-phosphopyridoxyl)-canaline, andN-(5-phosphopyridoxyl)-,-diaminobutyric acid (Seph-DAB-PLP), designed for binding specifically brain glutamate decarboxylase (GAD). The three Sepharose-N-(phosphopyridoxyl)-amino acids were capable of binding GAD from a mouse brain soluble preparation. The enzyme can be purified up to 25-fold in one step by affinity chromatography on Seph-DAB-PLP.Part of this work was presented at the VI Meeting of the American Society for Neurochemistry, Mexico City, March 10–14, 1975. 相似文献
14.
Jacques Raymond Jean Michel Robin Jean Louis Azanza 《Plant Systematics and Evolution》1995,198(3-4):195-208
The seeds of 19 sunflower species were compared on the basis of their protein contents and the relative proportions of their protein fractions. The globulin content varied from 50% to about 70% and the albumin content from 18% to 35% according to the species. The level of intermediateMr polypeptides showed a great variability (9.6 to 24.3%). Comparative studies onMr polymorphism were carried out by means of sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of non reduced and/or reduced samples using both mono- and bidimensional procedures. Polypeptide constituents of helianthinin were compared including both number and molecular size (cultivatedH. annuus was used as a standard). Studies focused on differences observed between the major two (Mr 38 000), (Mr 32 000) and (Mr 25 500), (21 000) polypeptides families constituting the main A, B, and C subunits. and polypeptides analyses permit to discriminate easilyH. petiolaris from the other species. Charge polymorphism was studied using isoelectric focusing (IEF) and IEF-PAGE in mono and bidimensional procedures in the presence or absence of 2-mercaptoethanol (2-ME). Only a specific 4 polypeptide enables an easy discrimination betweenH. petiolaris and all the other species. Detailed nomenclature of the , and , polypeptides constituting the different helianthinin globulin subunits is given via the results of pI andMr analyses. Monodimensional IEF patterns of the more basic albumins (pI > 8.0) appear to provide a more valuable approach to identifying specific protein markers. 相似文献
15.
Different molecular capacity in the induction of apoptosis by polychlorinated biphenyl congeners in rat renal tubular cell cultures 总被引:1,自引:0,他引:1
Pérez-Reyes PL Sánchez-Alonso JA López-Aparicio P Recio MN Pérez-Albarsanz MA 《Bioscience reports》2001,21(6):765-778
The effects of a commercial polychlorinated biphenyl (PCB) mixture (Aroclor 1248) and two individual PCB congeners were evaluated on rat renal proximal tubule culture cell viability and internucleosomal DNA fragmentation (DNA ladder) characteristic of apoptosis. Treatment with Aroclor 1248 caused the loss of cell viability and promoted apoptosis in a concentration- and time-dependent manner. The two PCB congeners assessed can also induce apoptosis. However, the extent of apoptosis generated was greater for the non-ortho-substituted planar congener (3,3,4,4-tetrachlorobiphenyl) than for the di-ortho-substituted nonplanar congener (2,2,4,4,5,5-hexachlorobiphenyl). This correlated with the loss of cell viability since the planar compound is much more cytotoxic. The results suggest a different molecular mechanism in the induction of apoptosis by planar or nonplanar PCB congeners. 相似文献
16.
G. Stotz P. de Vlaming H. Wiering A. W. Schram G. Forkmann 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,70(3):300-305
Summary In flower extracts of defined genotypes of Petunia hybrida, an enzyme activity was demonstrated which catalyses the hydroxylation of naringenin and dihydrokaempferol in the 3-position. Similar to the flavonoid 3-hydroxylases of other plants, the enzyme activity was found to be localized in the microsomal fraction and the reaction required NADPH as cofactor. A strict correlation was found between 3-hydroxylase activity and the gene Ht1, which is known to be involved in the hydroxylation of flavonoids in the 3-position in Petunia. Thus, the introduction of the 3-hydroxyl group is clearly achieved by hydroxylation of C15-intermediates, and the concomitant occurrence of the 3,4-hydroxylated flavonoids quercetin and cyanidin (paeonidin) in the presence of the functional allele Ht1 is due to the action of one specific hydroxylase catalysing the hydroxylation of common precursors for both flavonols and anthocyanins. 相似文献
17.
Miguel A. Diez Ibañez Martine Chessebeuf-Padieu Patrice Nordmann Prudent Padieu 《Cell biology and toxicology》1987,3(3):327-340
A new technique for the conversion of 2-acetylaminofuorene and several ring-hydroxylated metabolites to mono- and di-tert.-butyldimethylsilyl derivatives was developed to permit their analysis by gas chromatography-mass spectrometry in order to quantify the metabolism of 2-acetylaminofluorene incubated in freshly isolated rat hepatocytes. This new gas chromatography-mass spectrometry method allowed the separation, identification and quantitation of seven known metabolites comprising five arylhydroxylated compounds, 2-aminofuorene and N-hydroxy-2-acetylaminofuorene.Abbreviations 2-AAF
2-acetylaminofluorene
- 2-AF
2-aminofluorene
- DMF
dimethylformamide
- El
electron impact ionization
- FBS
fetal bovine serum
- GC-MS
gas chromatography-mass spectrometry
- MtBSTFA
N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide
- MU
methylene unit
- N-OH-2-AAF
N-hydroxy-2-acetylaminofluorene
- 4,4-OH-BP
4,4-hydroxybiphenyl
- tBDMS
tert.-butyldimethylsilyl 相似文献
18.
Toshikazu Oki Akihiro Yoshimoto Tatsuo Ogasawara Seiji Sato Akira Takamatsu 《Archives of microbiology》1976,107(2):183-187
The occurrence of adenosine 5-triphosphate-3-diphosphate-synthesizing activity was detected in five strains of actinomycetes; Streptomyces morookaensis, Streptomyces aspergilloides, Streptomyces hachijoensis, Actinomyces violascens and Streptoverticillium septatum, out of 825 strains of actinomycetes, bacteria, fungi and imperfecti. Purine nucleotide pyrophosphotransferase were extracellularly excreted associating with the cell growth, and were purified partially or to apparent homogeniety from the culture filtrate. The enzymes are a monomeric protein with a molecular weight of 18000–26000 and synthesize adenosine, guanosine and inosine 5-phosphate (mono, di or tri)-3-diphosphate such as pApp, ppApp, pppApp, pGpp, ppGpp, pppGpp and pppIpp by transferring a pyrophosphoryl group from the 5-position of ATP, dATP and pppApp to the 3-position of purine nucleotides in the presence of a divalent cation and in alkaline state.Abbreviations pppApp
adenosine 5-triphosphate 3-diphosphate
- ppApp
adenosine 5-diphosphate 3-diphosphate
- pApp
adenosine 5-monophosphate 3-diphosphate
- pppGpp
guanosine 5-triphosphate 3-diphosphate 相似文献
19.
Summary The plasmalemma ofNitella internode was made freely permeable to solutes by treating the cell with detergent and EGTA under plasmolysis. After the treatment, the cytoplasmic streaming was stopped by bathing the cell in a medium lacking ATP. The streaming was reactivated by perfusing the exterior of the permeabilized cell with a medium containing both Mg2+ and ATP. The reactivated streaming could be reversibly stopped by depletion of ATP. However, depletion of Mg2+ irreversibly inhibited the streaming.Cytochalasin B at 5 g/ml irreversibly inhibited the reactivated streaming within a minute, showing that microfilaments are involved in the streaming.Abbreviations ATP
adenosine-5-triphosphoric acid
- CB
cytochalasin B
- CyDTA
cyclohexanediamine-N,N-tetraacetic acid
- DMSO
dimethylsulfooxide
- DTT
dithiothreitol
- EGTA
ethyleneglycol-bis(-aminoethylether)-N,N tetraacetic acid
- PIPES
piperazine-N,N-bis(2-ethanesulfonic acid)
- PMSF
phenylmethyl-sulfonylfluoride 相似文献
20.
Summary We have synthesized 2(3)-O-(glycyl)-adenosine-5-(O-methylphos-phate), an analogue of the 3-terminus of aminoacylated tRNA. A 0.4M solution of this compound maintained at pH 8.2, yields 5.5% of diglycine and 11.5% of diketopiperazine, in addition to the hydrolysis products glycine and adenosine-5-(O-methylphosphate). Under the same conditions, glycine ethyl ester reacts much more slowly, but ultimately gives similar yields of diglycine and diketopiperazine.The aminolysis of 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) by free glycine is relatively inefficient, but serine reacts 20 times more rapidly and yields up to 50% of N-glycylserine. The prebiotic significance of these reactions is discussed.Abbreviations MepA
adenosine-5-(O-methylphosphate)
- MepA-gly
2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate)
- MepA-bis-gly
2,3-O-(bis-glycyl)-adenosine-5-(O-methylphosphate)
- DKP
diketopiperazine
- gly Et
glycine ethyl ester
- gly-ser
N-glycylserine
- O-gly-ser
O-glycylserine
- O-(gly)-gly-ser
O-(glycyl)-glycylserine
- Boc-gly
N-tert-butyloxycarbonylglycine
- MepA-Boc-gly
2(3)-O-(Boc-glycyl)-adenosine-5-(O-methylphosphate)
- MepA-bis-Boc-gly
2,3-O-(bis-Boc-glycyl)-adenosine-5(O-methylphosphate)
- (gly)2
diglycine
- (gly)3
triglycine 相似文献