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1.
H K Malviya S Parwekar R C Rajak S K Hasija 《Indian journal of experimental biology》1992,30(2):103-106
During hair degradation, majority of organic sulphur was oxidized to inorganic sulphate and thiosulphate by four fungal isolates (Cylindrocarpon lichenicola, Graphium cuneiferum, Microsporum gypseum, and M. fulvum) from gelatin factory soil. Inorganic thiosulphate, an unusual metabolite, was regularly detected in the culture filtrates of all fungi, although in less amounts. Maximum quantity (44 micrograms/ml) was released by G. cuneiferum on 50th day of incubation. All four fungi showed significant extracellular keratinase activity on human hair. Sulphydryl compounds were present in low amounts throughout the experiment. Detection of inorganic sulphate and thiosulphate with significant release of total protein and keratinase and changes in alkalinity, established the role of sulphitolysis and peptidolysis during keratin biodegradation by fungi which ultimately results in complete keratin degradation. 相似文献
2.
The beta-mannosyltransferase that catalyzes the synthesis of Man-beta-GlcNAc-GlcNAc-PP-dolichol from GDP-mannose and dolichyl-PP-GlcNAc-GlcNAc was solubilized from microsomes of suspension-cultured soybean cells by treatment with 1.5% Triton X-100 and was purified about 700-fold by chromatography on DEAE-cellulose, hydroxylapatite, and a GDP affinity column. The purified enzyme was reasonably stable in the presence of 20% glycerol and 0.5 mM dithiothreitol. The enzyme required either detergent (Triton X-100 or NP-40) or phospholipid for maximum activity, but the effects of these two were not additive. Thus, either phosphatidylcholine or Triton X-100 could give maximum stimulation. In terms of phospholipid stimulation, both the head group and the acyl chain appeared to be important since phosphatidylcholines with 18-carbon unsaturated fatty acids were most effective. The purified enzyme had a sharp pH optimum of 6.9-7.0 and required a divalent cation. Mg2+ was the best metal ion with optimum activity occurring at 6 mM, but Mn2+ was reasonably effective while Ca2+ was slightly stimulatory. The Km for GDP-mannose was calculated to be 1.7 X 10(-6) M and that for dolichyl-PP-GlcNAc-GlcNAc about 9 X 10(-6) M. The enzyme was inhibited by a number of guanosine nucleotides such as GDP-glucose, GDP, GMP, and GTP, but various uridine and adenosine nucleotides were without effect. The purified enzyme was apparently free of alpha-1,3-mannosyltransferase (and perhaps other mannosyltransferases) and dolichyl-P-mannose synthase since the only product seen from dolichyl-PP-GlcNAc-GlcNAc and GDP-mannose was Man-beta-GlcNAc-GlcNAc-PP-dolichol.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
3.
J E Tropea R J Molyneux G P Kaushal Y T Pan M Mitchell A D Elbein 《Biochemistry》1989,28(5):2027-2034
Australine [(1R,2R,3R,7S,7aR)-3-(hydroxymethyl)-1,2,7-trihydroxypyrrolizid ine] is a polyhydroxylated pyrrolizidine alkaloid that was isolated from the seeds of the Australian tree Castanospermum australe and characterized by NMR and X-ray diffraction analysis [Molyneux et al. (1988) J. Nat. Prod. (in press)]. Since swainsonine and catanospermine are polyhydroxylated indolizidine alkaloids that inhibit specific glycosidases, we tested australine against a variety of exoglycosidases to determine whether it would inhibit any of these enzymes. This alkaloid proved to be a good inhibitor of the alpha-glucosidase amyloglucosidase (50% inhibition at 5.8 microM), but it did not inhibit beta-glucosidase, alpha- or beta-mannosidase, or alpha- or beta-galactosidase. The inhibition of amyloglucosidase was of a competitive nature. Australine also inhibited the glycoprotein processing enzyme glucosidase I, but had only slight activity toward glucosidase II. When incubated with cultured cells, this alkaloid inhibited glycoprotein processing at the glucosidase I step and caused the accumulation of glycoproteins with Glc3Man7-9(GlcNAc)2-oligosaccharides. 相似文献
4.
Pastuszak Irena; Kaushal G.P.; Wall K.A.; Pan Y.T.; Sturm A.; Elbein A.D. 《Glycobiology》1990,1(1):71-82
Two arylmannosidases (signified as A and B) were purified tohomogeneity from soluble and microsomal fractions of mung beanseedlings. Arylmannosidase A from the microsomes appeared thesame on native gels and on SDS gels as soluble arylmannosidaseA, the same was true for arylmannosidase B. Sedimentation velocitystudies indicated that both enzymes were homogeneous, and thatarylmannosidase A had a molecular mass of 237 kd while B hada molecular mass of 243 kd. Arylmannosidase A showed two majorprotein bands on SDS gels with molecular masses of 60 and 55kd, and minor bands of 79, 39 and 35 kd. All of these bandswere N-linked since they were susceptible to digestion by endo-glucosaminidaseH. In addition, at least the major bands could be detected byWestern blots with antibody raised against the xylose moietyof N-linked plant oligosaccharides, and they could also be labeledin soybean suspension cells with [23H]mannose. ArylmannosidaseB showed three major bands with molecular masses of 72, 55 and45 kd, and minor bands of 42 and 39 kd. With the possible exceptionof the 45 and 42 kd bands, all of these bands are glycoproteins.Arylmannosidases A and B showed somewhat different kineticsin terms of mannose release from high-mannose oligosaccharides,but they were equally susceptible to inhibition by swainsonineand mannostatin A. Polyclonal antibody raised against the arylmannosidaseB cross-reacted equally well with arylmannosidase A from mungbean seedlings and with arylmannosidase from soybean cells.However, monoclonal antibody against mung bean arylmannosidaseA was much less effective against arylmannosidase B. Antibodywas used to examine the biosynthesis and structure of the carbohydratechains of arylmannosidase in soybean cells grown in [23H]mannose.Treatment of the purified enzyme with Endo H released 50% ofthe radioactivity, and these labeled oligosaccharides were ofthe high-mannose type, i.e. mostly Man9GlcNAc. The precipitatedprotein isolated from the Endo H treatment still contained 50%of the radioactivity, and this was present in modified structuresthat probably contain xylose residues. Mung beans mannosidases glycoproteins -soybean--mannosidases xylose-containing N-linked glycoproteins 相似文献
5.
Absidia cylindrospora and Rhizomucor pusillus, causal agents of phycomycoses, were cultured on sterile natural keratins in a mineral solution and the keratin degradation products analyzed. The excess of sulphur was removed by oxidation to inorganic sulphate and thiosulphate, which were the main products of sulphitolysis of keratin. The proteolytic activity of the two fungi depended on the nature of the keratin substrate. Human scalp hair was the most favoured keratin substrate by both the fungi. 相似文献
6.
Selective inhibition of glycoprotein-processing enzymes. Differential inhibition of glucosidases I and II in cell culture 总被引:1,自引:0,他引:1
G P Kaushal Y T Pan J E Tropea M Mitchell P Liu A D Elbein 《The Journal of biological chemistry》1988,263(33):17278-17283
In this study, we compared the effects of 2,6-dideoxy-2,6-imino-7-O-(beta-D-glucopyranosyl)-D-glycero-L-gulohep titol (MDL) to those of the glucosidase I inhibitor, castanospermine, on the purified processing enzymes glucosidases I and II. WE also compared the effects of these two inhibitors on glycoprotein processing in cell culture using influenza virus-infected Madin-Darby canine kidney cells as a model system. With the purified processing enzymes, castanospermine was a better inhibitor of glucosidase I than of glucosidase II, whereas MDL is more effective against glucosidase II than glucosidase I. In cell culture at the appropriate dose, MDL also preferentially affected glucosidase II. Thus, at 250 micrograms/ml MDL, the major [3H]glucose-labeled (or [3H]mannose-labeled) glycopeptide from the viral hemagglutinin was susceptible to endoglucosaminidase H, and the oligosaccharide liberated by this treatment was characterized as a Glc2Man7-9GlcNAc on the basis of size, resistance to digestion by glucosidase I (but sensitivity to glucosidase II), methylation analysis, and Smith degradation studies. These data indicate that at appropriate concentrations of MDL (250 micrograms/ml), one can selectively inhibit glucosidase II in Madin-Darby canine kidney cells. However, at higher concentrations of inhibitor (500 micrograms/ml), both enzymes are apparently affected. Since MDL did not greatly inhibit the synthesis of lipid-linked saccharides or the synthesis of protein or RNA, it should be a useful tool for studies on the biosynthesis and role of N-linked oligosaccharides in glycoprotein function. 相似文献
7.
Properties of Solubilized UDP-GlcNAc: Dolichyl Phosphate-GlcNAc-1-P-Transferase from Soybean Cultured Cells 总被引:1,自引:1,他引:0
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The GlcNAc-1-P-transferase was solubilized from microsomal preparations of soybean cultured cells by treatment with 1% Triton X-100. The solubilized enzyme catalyzed the formation of dolichyl pyrophosphoryl-GlcNAc when incubated with UDP-GlcNAc and dolichyl phosphate. The GlcNAc-1-P-transferase activity was stimulated by the addition of phosphatidylglycerol and phosphatidylinositol, but was inhibited by phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine. The Km value for dolichyl-phosphate was 6.2 micromolar and that determined for UDP-GlcNAc was 0.42 micromolar. The pH optimum for the GlcNAc-1-P reaction was between 7.2 and 7.6; maximum activity occurred at about 10 millimolar Mg2+. The addition of unlabeled GDP-mannose or UDP-glucose considerably inhibited enzyme activity which could be restored to nearly the original value by addition of more dolichyl phosphate to the incubation mixture. On the other hand, the addition of unlabeled ADP-glucose and GDP-glucose enhanced the enzyme activity. This stimulation by these sugar nucleotides was found to be due to the protection of the substrate UDP-[3H]-GlcNAc from pyrophosphatase degradation. The GlcNAc-1-P-transferase reaction was very sensitive to tunicamycin and 50% inhibition required less than 1 microgram of antibiotic per milliliter. Amphomycin, showdomycin, and diumycin also inhibited this reaction but at higher concentrations. 相似文献
8.
Fucosylation of membrane proteins in soybean cultured cells : effects of tunicamycin and swainsonine 总被引:3,自引:2,他引:1
Cultures of soybean cells incorporate [5,6-3H]-l-fucose into various cellular components including lipids and proteins. The membrane glyco-proteins were digested with pronase to produce glycopeptides, and the glycopeptides were isolated on columns of Biogel P-4. The major fucoselabeled glycopeptide sized as a Hexose15-17-N-acetylglucosamine2 (GlcNAc2) on columns of Biogel P-4. Fucose incorporation was also examined in the presence of the processing inhibitor swainsonine, and the glycosylation inhibitor tunicamycin. In the presence of swainsonine, the incorporation of fucose was not reduced but the glycopeptides were smaller in size and migrated like Hexose12-13-GlcNAc2 structures. On the other hand, tunicamycin inhibited the incorporation of fucose into the glycopeptides by 70 to 80%, indicating that the l-fucose was present in N-linked oligosaccharides. 相似文献
9.
Structure and synthesis of histopine, a histidine derivative produced by crown gall tumors 总被引:2,自引:0,他引:2
Histopine, an unusual amino acid derivative of histidine isolated from crown gall tumors of sunflowers (Helianthus annus) inoculated with Agrobacterium tumefaciens strain B6, was previously assigned the gross structure N-(1-carboxyethyl) histidine (2). A diastereomeric mixture containing histopine (2a and 2b) was readily prepared by reductive alkylation of (S)-histidine (1) with pyruvic acid and sodium cyanoborohydride. The individual diastereomers were prepared by reaction of (S)-histidine with (R)- and (S)-2-bromopropionic acid. (R)-N-(1-Carboxyethyl)-(S)-histidine (2a) supports the growth of A. tumefaciens whereas (S)-N-(1-carboxyethyl)-(S)-histidine (2b) is inactive. Therefore, we assign structure 2a to histopine. 相似文献
10.
Sarvesh Adda T. P. Reddy P. B. Kavi Kishor 《In vitro cellular & developmental biology. Plant》1994,30(2):104-107
Summary Induction of somatic embryogenesis, shoot organogenesis, and subsequent plant regeneration in niger seem to be dependent on
genotype, choice of explant, and composition of media growth regulators. Two distinct regeneration protocols have been developed
for somatic embryogenesis and shoot organogenesis. Somatic embryogenesis was induced from epicotyls and cotyledonary explants
(9 to 35%) (but not from hypocotyls and roots) in presence of 2,4-dichlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic
acid, and 2,4,5-trichlorophenoxypropionic acid. These embryos matured in MS medium containing Kinetin plus naphthalene acetic
acid (NAA), Kinetin plus Zeatin, and Kinetin plus abscisic acid (ABA). Matured embryos could be germinated on LS and MS basal
media without hormones. Non-embryogenic callus initiated on Linsmaier and Skoog’s (LS) medium from cotyledons of six
different genotypes produced shoots (9 to 32%) on Murashige and Skoog’s (MS) medium fortified with 6-benzylaminopurine
(BAP, 0.5 mg · liter−1), and BAP (1 mg · liter−1) plus NAA (0.1 mg · liter−1). These shoots were rooted with 100% frequency by using indole-3-acetic acid or NAA and transferred successfully to the soil. 相似文献