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1.
(DL Lys)10–(L Val)20–(DL Lys)10, a copolymer of a valine block in the β conformation with randomly coiled flanking blocks of lysine [Kubota, S. & Fasman, G. D. (1975) Biopolymers 14 , 605–631], was studied by nuclear magnetic resonance. The peak areas of the N? H and C? H resonances of valine and lysine are concentration-dependent with little chemical shift change. A model is presented describing the aggregation of the copolymer. Additional evidence, obtained by monitoring the spin-lattice relaxation times of amino, amide, γ-methyl-valine, and ?-methylene-lysine, is consistent with the aggregation model. Hydrodynamic studies are presented which show monomer → oligomer aggregation of four or five subunits.  相似文献   

2.
The action on tamarind seed xyloglucan of the pure, xyloglucan-specific endo-(1→4)-β-D-glucanase from nasturtium (Tropaeolum majus L.) cotyledons has been compared with that of a pure endo-(1→4)-β-D-glucanase (‘cellulase’) of fungal origin. The fungal enzyme hydrolysed the polysaccharide almost completely to a mixture of the four xyloglucan oligosaccharides: Exhaustive digestion with the nasturtium enzyme gave the same four oligosaccharides plus large amounts of higher oligosaccharides and higher-polymeric material. Five of the product oligosaccharides (D,E,F,G,H) were purified and shown to be dimers of oligosaccharides A to C. D (glc8xyl6) had the structure A→A, H (glc8xyl6gal4) was C→C, whereas E (glc8xyl6gal), F (glc8xyl6gal2) and G (glc8xyl6gal3) were mixtures of structural isomers with the appropriate composition. For example, F contained B2→B2 (30%), A→C (30%), C→A (20%), B2B1 (15%) and others (about 5%). At moderate concentration (about 3 mM) oligosaccharides D to H were not further hydrolysed by the nasturtium enzyme, but underwent transglycosylation to give oligosaccharides from the group A, B, C, plus higher oligomeric structures. At lower substrate concentrations, hydrolysis was observed. Similarly, tamarind seed xyloglucan was hydrolysed to a greater extent at lower concentrations. It is concluded that the xyloglucan-specific nasturtium-seed endo-(1→4)-β-D-glucanase has a powerful xyloglucan-xyloglucan endo-transglycosylase activity in addition to its known xyloglucan-specific hydrolytic action. It would be more appropriately classified as a xyloglucan endo-transglycosylase. The action and specificity of the nasturtium enzyme are discussed in the context of xyloglucan metabolism in the cell walls of seeds and in other plant tissues.  相似文献   

3.
Construction of 25-hydroxy-steroidal side chain substituted with iodine at C-22 was elaborated on a model PTAD-protected steroidal 5,7-diene and applied to a synthesis of (22R)- and (22S)-22-iodo-1α,25-dihydroxyvitamin D3. Configuration at C-22 in the iodinated vitamins, obtained by nucleophilic substitution of the corresponding 22S-tosylates with sodium iodide, was determined by comparison of their iodine-displacement processes and cyclizations leading to isomeric five-membered (22,25)-epoxy-1α-hydroxyvitamin D3 compounds. Also, 20(22)-dehydrosteroids have been obtained and their structures established by 1H NMR spectroscopy. When compared to the natural hormone, (E)-20(22)-dehydro-1α,25-dihydroxyvitamin D3 was found 4 times less potent in binding to the porcine intestinal vitamin D receptor (VDR) and 2 times less effective in differentiation of HL-60 cells. 22-Iodinated vitamin D analogues showed somewhat lower in vitro activity, whereas (22,25)-epoxy analogues were inactive. Interestingly, it was established that (22S)-22-iodo-1α,25-dihydroxyvitamin D3 was 3 times more potent than its (22R)-isomer in binding to VDR and four times more effective in HL-60 cell differentiation assay. The restricted mobility of the side chain of both 22-iodinated vitamin D compounds was analyzed by a systematic conformational search indicating different spatial regions occupied by their 25-oxygen atoms. Preliminary data on the in vivo calcemic activity of the synthesized vitamin D analogues indicate that (E)-20(22)-dehydro-1α,25-dihydroxyvitamin D3 and 22-iodo-1α,25-dihydroxyvitamin D3 isomers were ca. ten times less potent than the natural hormone 1α,25-(OH)2D3 both in intestinal calcium transport and bone calcium mobilization.  相似文献   

4.
Summary In situ hybridisation and restriction fragment length polymorphism (RFLP) analysis were used to determine the relative location of the translocation breakpoint and the size of the integrated chromatin segment in hexaploid wheat-Lophopyrum translocation stocks. Three 7el2-7D recombinant stocks were Robertsonian translocations, 7DS.7el. The remaining recombinant stock (KS10-2) was 7elS.7el-7DL and contained only the distal one-half of the long arm of 7D. The recombinant stock with 7el1 (K11695) could be designated 7DS.7DL-7el where approximately the distal one-half of 7DL was replaced. RFLP analysis indicated that on the 7DL RFLP map the breakpoints for K11695 and KS10-2 are in different locations and that the two recombinants contain an overlapping region (a common region) of the Lophopyrum chromosome 7 in which Lr19, a leaf-rust resistant gene, is located. RFLP analysis also indicated that RFLP markers which mapped to within 1.5 cm of the centromere of chromosome 7D are located in the distal half of the long arm.  相似文献   

5.
Objective: To investigate the ability of 1,25(OH)2D3 (D) and genistein (G), alone and in combination, to inhibit adipogenesis and induce apoptosis in 3T3‐L1 adipocytes. Methods and Procedures: 3T3‐L1 preadipocytes and mature adipocytes were incubated with various concentrations of D and G, alone and in combination, for 48 h. Viability was determined using the Cell Titer 96 Aqueous One Solution Cell Proliferation Assay. Post‐confluent preadipocytes were incubated with D and G for up to 6 days during adipogenesis and lipid content was quantified by Nile Red dye; apoptosis was quantified by measurement of single‐stranded DNA. Expression of adipocyte‐specific proteins and VDR was analyzed by western blotting. Results: Combining D and G did not cause an enhanced effect on cell viability in either preadipocytes or mature adipocytes. In maturing preadipocytes, D at 0.5 nmol/l (D0.5) increased apoptosis by 47 ± 10.25% (P < 0.05) and inhibited lipid accumulation by 28 ± 10% (P < 0.001), while G at 25 μmol/l (G25) had no significant effect. However, D+G caused an enhanced apoptosis by 136 ± 12.6% (P < 0.001) and enhanced inhibition of lipid accumulation by 82.46 ± 2.95% (P < 0.001). Similarly, D0.5 alone decreased adipose‐specific gene 422 (aP2) expression to 34.2 ± 2.3% and increased VDR expression levels by 41.8 ± 11% (P < 0.001), but G25 showed no effect. However, D0.5+G25 decreased aP2 expression to 52 ± 4.2% (P < 0.05) and increased VDR expression levels by 131 ± 14.5% (P < 0.0001). Discussion: These findings suggest that combining 1,25(OH)2D3 with genistein results in an enhanced inhibition of lipid accumulation and induction of apoptosis in maturing 3T3‐L1 preadipocytes.  相似文献   

6.
Activation of precursor 25‐hydroxyvitamin D3 (25D) to hormonal 1,25‐dihydroxyvitamin D3 (1,25D) is a pivotal step in vitamin D physiology, catalysed by the enzyme 25‐hydroxyvitamin D‐1α‐hydroxylase (1α‐hydroxylase). To establish new models for assessing the physiological importance of the 1α‐hydroxylase‐25D‐axis, we used Danio rerio (zebrafish) to characterize expression and biological activity of the gene for 1α‐hydroxylase (cyp27b1). Treatment of day 5 zebrafish larvae with inactive 25D (5–150 nM) or active 1,25D (0.1–10 nM) induced dose responsive expression (15–95‐fold) of the vitamin D‐target gene cyp24a1 relative to larvae treated with vehicle, suggesting the presence of Cyp27b1 activity. A full‐length zebrafish cyp27b1 cDNA was then generated using RACE and RT‐PCR methods. Sequencing of the resulting clone revealed an open reading frame encoding a protein of 505 amino acids with 54% identity to human CYP27B1. Transfection of a cyp27b1 expression vector into HKC‐8, a human kidney proximal tubular epithelial cell line, enhanced intracrine metabolism of 25D to 1,25D resulting in greater than twofold induction of CYP24A1 mRNA expression and a 25‐fold increase in 1,25D production compared to empty vector. These data indicate that we have cloned a functional zebrafish CYP27B1, representing a phylogenetically distant branch from mammals of this key enzyme in vitamin D metabolism. Further analysis of cyp27b1 expression and activity in zebrafish may provide new perspectives on the biological importance of 25D metabolism. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

7.
《Chirality》2017,29(6):273-281
Enantiomeric 1H and 13C NMR signal separation behaviors of various α‐amino acids and DL‐tartarate were investigated by using the samarium(III) and neodymium(III) complexes with (S ,S )‐ethylenediamine‐N ,N' ‐disuccinate as chiral shift reagents. A relatively smaller concentration ratio of the lanthanide(III) complex to substrates was suitable for the neodymium(III) complex compared with the samarium(III) one, striking a balance between relatively greater signal separation and broadening. To clarify the difference in the signal separation behavior, the chemical shifts of β‐protons for fully bound D‐ and L‐alanine (δb(D) and δb(L)) and their adduct formation constants (K s) were obtained for both metal complexes. Preference for D‐alanine was similarly observed for both complexes, while it was revealed that the difference between the δb(D) and δb(L) values is the significant factor to determine the enantiomeric signal separation. The neodymium(III) and samarium(III) complexes can be used complementarily for higher and smaller concentration ranges of substrates, respectively, because the neodymium(III) complex gives the larger difference between the δb(D) and δb(L) values with greater signal broadening compared to the samarium(III) complex.  相似文献   

8.
The present study was undertaken to examine the influence of the reversal of the sidechain sequential order on the conformation of branched polypeptides. At the same time, the influence of the optically active amino acid joined directly to the poly (L -Lys) backbone and the DL -Ala oligomer grafted as chain-terminating fragment were separately analyzed. Therefore two sets of polypeptides were synthesized corresponding to the general formula poly [Lys-(Xi,)] (XK) and poly[Lys-(DL -Alam-Xi)] (AXK) when X = Ala, D -Ala, Leu, D -Leu, Phe, D -Phe, Ile, Pro, Glu.,D -Glu, or His. For coupling amino acid X to polylysine, three types of active ester methods were compared: the use of pentafluorophenyl or pentachlorophenyl ester, and the effect of the addition of an equimolar amount of 1-hydroxybenzotriazole. After cleavage of protecting groups, AXK polypeptides were synthesized by grafting short oligo (DL -Ala) chains to XK by using N-carboxy-DL -Ala anhydride. The CD measurements performed in water solutions of various pH values and ionic strengths were used for classification of the polypeptide conformations as either ordered (helical) or unordered. Different from what was observed with the unsubstituted poly (L -Lys), poly[Lys-(Xi)] type polypeptides can adopt ordered structure even under nearly physiological conditions (pH 7.3, 0.2M NaCl). These data suggest that the introduction of amino acid residue with either (ar) alkyl side chain (Ala, Leu, Phe) or negatively charged side chain (Glu) promotes markedly the formation of ordered structure. Comparison of chiroptical properties of poly [Lys- (DL -Alam-Xi)] and of poly [Lys- (Xi)] reveals that side-chain interactions play an important role in the stabilization of ordered solution conformation of AXK type branched polypeptides. The results give rather conclusive evidence that not only hydrophobic interactions, but also ionic attraction, can be involved in the formation and stabilization of helical conformation of branched polypeptides. © 1993 John Wiley & Sons, Inc.  相似文献   

9.
T Iio 《Biopolymers》1971,10(9):1583-1596
Sequential polypeptides of L -alanine(A) and glycine(G), which were incorporated between two blocks of poly(D ,L -glutamic acid) (DL), were synthesized by applying Merri-field's solid-phase method. On the basis of optical rotatory dispersion criteria, DL(A)38-DL was found to assume the α-helix in the whole range of the water-methanol system; whereas other block sequential polypeptides were found to assume the random-coiled conformation in water and partly the α-helix at the high methanol content. The stability of the α-helix decreased in the order: DL(A)38DL, DL(A2G)10DL, DL(A2G)6DL, and DL(A3G)7DL. This phenomenon may be explained in terms of the dependence of hydrophobic bonding between the C3H group of the ith L -alanine regularly arranged on the surface of the α-helix and the C2H group of the (i + 3)th residue on whether the residue is alanine or glycine. The role which the methanol plays in stabilizing the α-helix is also discussed.  相似文献   

10.
11.
The seasonal changes of photosynthesis of cones of Japanese larch (Larix kaempferi Carr.) trees showed that gross photosynthetic rate of young cones (P G) was 2–3 μmol m−2 s−1 at surface area unit and P G/R D (dark respiration of cones) peaked about 0.7 in the same period, indicating that 70 % of respiratory CO2 was re-fixed. With maturation, P G and P G/R D sharply decreased. Chlorophyll content in cones was 3–20 % of that in leaves, which made it a limiting factor for photosynthesis and its content was closely correlated with photosynthetic capacity. Although sunken and linearly arranged stomatal organs were found on the scale of young cones, differently from the significant regulation of leaf photosynthesis, these stomata tended to be non-functional since CO2 is not limiting factor for cone photosynthesis. Thus photosynthesis of larch cones is an additional contribution to their development.  相似文献   

12.
The Swiss winter bread wheat cv. Forno has a highly effective, durable and quantitative leaf rust (Puccinia triticina Eriks.) resistance which is associated with leaf tip necrosis (LTN). We studied 240 single seed descent lines of an Arina×Forno F5:7 population to identify and map quantitative trait loci (QTLs) for leaf rust resistance and LTN. Percentage of infected leaf area (%) and the response to infection (RI) were evaluated in seven field trials and were transformed to the area under the disease progress curves (AUDPC). Using composite interval mapping and LOD >4.4, we identified eight chromosomal regions specifically associated with resistance. The largest and most consistent leaf rust resistance locus was identified on the short arm of chromosome 7D (32.6% of variance explained for AUDPC_% and 42.6% for AUDPC_RI) together with the major QTL for LTN (R 2=55.6%) in the same chromosomal region as Lr34 (Xgwm295). A second major leaf rust resistance QTL (R 2=28% and 31.5%, respectively) was located on chromosome arm 1BS close to Xgwm604 and was not associated with LTN. Additional minor QTLs for LTN (2DL, 3DL, 4BS and 5AL) and leaf rust resistance were identified. These latter QTLs might correspond to the leaf rust resistance genes Lr2 or Lr22 (2DS) and Lr14a (7BL).Electronic Supplementary Material Supplementary material ist available in the online version ot this article at Communicated by H.C. Becker  相似文献   

13.
The circadian regulation of leaf hydraulic conductance (Kleaf) was investigated in Helianthus annuus L. (sunflower). Kleaf was measured with an high pressure flow meter during the light and dark period from plants growing at a photoperiod of 12 h. Kleaf was 4.0 e−4 kg s−1 m−2 MPa−1 during the light period (LL) and 30–40% less during the dark period (DL). When photoperiod was inverted and leaves were measured for Kleaf at their subjective light or dark periods, Kleaf adjusted to the new conditions requiring 48 h for increasing from dark to light values and 4 d for the opposite transition. Plants put in continuous dark showed Kleaf oscillating from light to dark values in phase with their subjective photoperiod indicating that Kleaf changes were induced by the circadian clock. Several cuts through the minor veins reduced leaf hydraulic resistance (Rleaf) of both LL and DL to the same value (1.0 e + 3 MPa m2 s kg−1) that equalled the vascular resistance (Rv). The contribution of the non-vascular leaf resistance (Rnv) to Rleaf was of 71.9% in DL and of 58.4% in LL. The dominant Rnv was shown to be reversibly modulated by mercurials, suggesting that aquaporins play a role in diurnal changes of Kleaf.  相似文献   

14.
Two alloplasmic wheat-barley substitution lines were studied: a line replaced at three pairs of chromosomes 1H mar (1B), 5H mar (5D), and 7H mar (7D), and the disomic-substituted line 7H mar (7D). The lines were constructed on the basis of individual plants from BC1F8 and BC2F6 progeny of barley-wheat hybrids (H. marinum subsp. gussoneanum Hudson (= H. geniculatum All.) (2n = 28) × T. aestivum L.) (2n = 42) (Pyrotrix 28), respectively. Moreover, the alloplasmic wheat-barley ditelosomic addition line 7HL mar isolated among plants from the BC1F6 progeny of a barley-wheat amphiploid was studied, which in this work corresponds to BC2F10 and BC2F11 progeny. It was ascertained that when grown in the field, these alloplasmic lines manifest stable self-fertility. Plants of the given lines are characterized by low height, shortened ears, the fewer number of stems and ears, and of spikelets in the ear, by decreased grain productivity and weight of 1000 grains, in comparison with the common wheat cultivar Pyrotrix 28. The inhibition of trait expression in alloplasmic wheat-barley substitution and addition lines may be connected not only with the influence of wild barley chromosomes functioning in the genotypic environment of common wheat, but also with the effect of the barley cytoplasm. The alloplasmic line with substitution of chromosomes 1H mar (1B), 5H mar (5D), and 7H mar (7D) or the alloplasmic line 5HL mar with ditelosomic addition have, in comparison with the common wheat cultivar Pyrotrix 28, an increased grain protein content, which is explained by the effect of wild barley H. marinum subsp. gussoneanum chromosomes.  相似文献   

15.
1α,25-Dihydroxy-2β-(3-hydroxypropoxy)vitamin D3 (ED-71), an analog of active vitamin D3, 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3], possesses a hydroxypropoxy substituent at the 2β-position of 1,25(OH)2D3. ED-71 has potent biological effects on bone and is currently under phase III clinical studies for bone fracture prevention. It is well-known that the synthesis and secretion of parathyroid hormone (PTH) is regulated by 1,25(OH)2D3. Interestingly, during clinical development of ED-71, serum intact PTH in osteoporotic patients did not change significantly upon treatment with ED-71. The reason remains unclear, however. Brown et al. reported that 3-epi-1,25(OH)2D3, an epimer of 1,25(OH)2D3 at the 3-position, shows equipotent and prolonged activity compared to 1,25(OH)2D3 at suppressing PTH secretion. Since ED-71 has a bulky hydroxypropoxy substituent at the 2-position, epimerization at the adjacent and sterically hindered 3-position might be prevented, which may account for its weak potency in PTH suppression observed in clinical studies. We have significant interest in ED-71 epimerization at the 3-position and the biological potency of 3-epi-ED-71 in suppressing PTH secretion. In the present studies, synthesis of 3-epi-ED-71 and investigations of in vitro suppression of PTH using bovine parathyroid cells are described. The inhibitory potency of vitamin D3 analogs were found to be 1,25(OH)2D3 > ED-71 ≥ 3-epi-1,25(OH)2D3  3-epi-ED-71. ED-71 and 3-epi-ED-71 showed weak activity towards PTH suppression in our assays.  相似文献   

16.
Summary Restriction fragment length polymorphism (RFLP) markers linked to genes controlling Hessian fly resistance from Triticum tauschii (Coss.) Schmal. were identified for two wheat (Triticum aestivum L.) germ plasm lines KS89WGRC3 (C3) and KS89WGRC6 (C6). Forty-six clones with loci on chromosomes of homoeologous group 3 and 28 clones on those of group 6 were surveyed for polymorphisms. Eleven and 12 clones detected T. tauschii loci in the two lines, respectively. Analysis of F2 progenies indicated that the Hessian fly resistance gene H23 identified in C3 is linked to XksuH4 (6.9 cM) and XksuG48 (A) (15.6 cM), located on 6D. The resistance gene H24 in C6 is linked to XcnlBCD451 (5.9 cM), XcnlCD0482 (5.9 cM) and XksuG48 (B) (12.9 cM), located on 3DL.Paper No. 810 of the Cornell Plant Breeding Series  相似文献   

17.
We postulated that dietary ingestion of vitamin D may be used by some Alaskan Arctic marine mammal species in addition to, or instead of, cutaneous production to meet nutritional requirements. Zooplankton (n=5) sampled near Kaktovik, Alaska, contained no measurable vitamin D2 or D3, but did contain provitamin D (7‐dehydrocholesterol), the cutaneous precursor for previtamin D3 in mammals. Fillets and livers from five fish species were sampled near Barrow, Alaska, and evaluated for vitamin D3 content (no vitamin D2 was detected). Differences in vitamin D3 content appeared significant (P≤0.10) among fish livers (Kruskal‐Wallis [H test]=8.25, df=4, P=0.08) and among fish fillets (H=7.80, df=4, P=0.01). We also found significant differences in several pairwise comparisons (Mann‐Whitney U‐test) of vitamin D3 levels in fillets and livers. Blubber from six species of marine mammals had no detectable vitamin D2. The H test results for blubber vitamin D3 concentration were highly significant: 28.12, df=5, P<0.001. There were also significant differences in vitamin D3 content from blubber in pairwise comparisons of primarily invertebrate feeders (bowhead whale (Balaena mysticetus) [mean=4.20 SD±1.10 ng/g], and Pacific walrus (Odobenus rosmarus divergens) [5.43±2.82 ng/g]) vs. primarily piscivorous feeders (ringed seal (Phoca hispida) [746.57±493.00 ng/g] and beluga whale (Delphinapterus leucas) [426.00±174.92 ng/g]) and a semiaquatic terrestrial carnivore (polar bear (Ursus maritimus) [406.17±311.70 ng/g]). The bearded seal (Erignathus barbatus) had intermediate blubber vitamin D3 concentration (156.83±139.25 ng/g), which may reflect an intermediate‐type feeding strategy or an artifact of the small sample size. Zoo Biol 23:33–43, 2004. © 2004 Wiley‐Liss, Inc.  相似文献   

18.
Excessive Zn but normal Cu and Mg in the staple food consumed by the people of Chandigarh (Union territory and capital of Punjab and Haryana States of India) has been considered to be the major risk factor for the prevalence of obesity (33.15%) and obesity-related diseases in this region. Therefore, in the present investigations, in obesity-related diseases, the status of these minerals was estimated in their tissues, including hair, nails, and blood serum and urine, and compared with those of normal subjects. They were grouped as: normal subjects in control Group A, middle-aged diabetics in Group DM, older diabetics in Group DO, and diabetics with osteoarthritis in Group D+ OA, osteoarthritis in Group OA and rheumatoid arthritis in Group RA, respectively. The results evaluated in the order as: hair Zn, group D+OA>DM>OA>A (control)>RA>DO (p < 0.001); hair Cu, group A (control)>DM>OA>D+OA>DO>RA (p < 0.001); hair Mg, group A (control)>DM>OA>D+OA>RA>DO (p < 0.001, 0.01); hair Mn, group A (control)>RA>OA>D-OA>DM>DO (p < 0.001); nail Zn, group DM>D+OA>OA>A (control)>RA>DO (p < 0.001, 0.05); nail Cu, group A (control)>OA>DM>D+OA>RA>DO (p < 0.001); nail Mg, group A (control)>OA>DM>DO>D+OA >RA (p < 0.001); nail Mn, group A (control) >RA>OA>D+OA>DM>DO (p < 0.01); urine Zn, group DO>DM>D+OA>A (control)>RA>OA (p < 0.01); urine Cu, group RA>D+OA>DO>OA> DM>A (control) (p<0.001); urine Mg, group RA>OA>D+OA>DO>DM>A (control; p < 0.001); urine Mn, group DO>DM>OA>D+OA>RA>A (control; p < 0.001), respectively. The analysis of the mineral status in serum of diabetics further showed their highly significant rise from lower mean age subgroup to higher mean age subgroup than their control counter parts (p < 0.001, 0.01, and 0.05) with coincident deficiencies of Cu, Mg, and Mn in their tissues. This study would be helpful considering the status of minerals in these obesity-related diseases depending on the choice of the food consumed to improve the quality of life and prognosis for the diseases.  相似文献   

19.
Galactomannans from the seeds of Ural licorice (Glycyrrhiza uralensis Fisch.) obtained by hot water extraction of freshly ripened (GGu-1) and overwintered (GGu-2) seeds were studied. GGu-1 and GGu-2 (yield, 1.98 and 1.99% of the seed weight) had molecular weights of 1379 and 877 kDa, respectively; their solutions were characterized by high viscosity ([η 1193.1 and 765.8 mg/g, respectively) and optical activity ([αD, +64.8 and +65.6 deg, respectively). Their galactose-to-mannose ratio was 1: 1.52 and 1: 1.50, respectively. According to IR and 13C NMR spectroscopic data and methylation analysis, the polymeric chains of GGu-1 and GGu-2 are comprised of 1,4-β-D-mannopyranose residues substituted at C-6 with single α-D-galactopyranose residues. The content of mannobiose units Man-Man, (Gal)Man-Man/Man-Man(Gal), and (Gal)Man-Man(Gal) differentially substituted with galactose in macromolecules GGu-1 and GGu-2 was 25.2, 18.4 and 55.9% for GGu-1 and 26.5, 32.5, and 41.0% for GGu-2.  相似文献   

20.
Galactomannan, a heteropolysaccharide with a molecular weight of 1660 kDa, was isolated from the seed of Gleditsia ferox Desf., introduced in Russia, with a yield of 18.9%. Its aqueous solutions were optically active ([]D = +30.5°) and highly viscous ([] = 1430 ml/g). An analysis of the heteropolysaccharide using chemical, enzymatic, and chromatographic procedures showed that it consists of D-mannopyranose and D-galactopyranose residues (molar ratio, 2.54 : 1). The main chain of this galactomannan consists of 1,4--D-mannopyranose residues, 39.2% of which are substituted at C6 with single residues of -D-galactopyranose. The probability of occurrence of mannobiose units differentially substituted with galactose was determined by 13C-NMR data and equaled, respectively, 0.37, 0.47, and 0.16 for non-substituted Man–Man units, monosubstituted Gal(Man–Man) and (Man–Man)Gal units taken together, and for the disubstituted Gal(Man–Man)Gal units.  相似文献   

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