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1.
Masanori Bun-ya Yoshitaka Muro Toshiro Niki Jun Kondo Tatsuyuki Kamiryo 《Cell biochemistry and biophysics》2000,32(1-3):107-116
Sterol carrier protein 2 (SCP2) is a 13-kDa peroxisomal protein, identical to nonspecific lipidtransfer protein, and stimulates
various steps of cholesterol metabolism in vitro. Although the name is reminiscent of acyl carrier protein, which is involved
in fatty acid synthesis, SCP2 does not bind to lipids specifically or stoichiometrically. This protein is expressed either
as a small precursor or as a large fusion (termed SCPx) that carries at its C-terminal the complete sequence of SCP2. SCPx
exhibits 3-oxoacyl-CoA thiolase activity, as well as sterol-carrier and lipid-transfer activities. The N- and C-terminal parts
of SCPx are similar to the nematode protein P-44 and the yeast protein PXP-18, respectively. P-44, which has no SCP2 sequence,
thiolytically cleaved the side chain of bile acid intermediate at a rate comparable to that of SCPx. This, together with the
properties of other fusions with SCP2-like sequence, suggests that the SCP2 part of SCPx does not play a direct role in thiolase
reaction. PXP-18, located predominantly inside peroxisomes, is similar to SCP2 in primary structure and lipid-transfer activity,
and protects peroxisomal acyl-CoA oxidase from thermal denaturation. PXP-18 dimerized at a high temperature, formed an equimolar
complex with the oxidase subunit, and released the active enzyme from the complex when the temperature went down. This article
attempts to gain insight into the role of SPC2, and to present a model in which PXP-18, a member of the SCP2 family, functions
as a molecular chaperone in peroxisomes. 相似文献
2.
The occurrence of a new bacterial dehalogenase acting on both the optical isomers of 2-halogenated alkanoic acids was demonstrated. When the haloalkanoic acid-utilizing bacteria were screened in a medium containing dl-2-chloropropionate as a sole carbon source, two types of bacteria were isolated: (1) a few strains utilizing both d- and l-isomers of 2-chloropropionate and (2) strains utilizing only the l-isomer. A dehalogenating enzyme was obtained from the cells of Pseudomonas sp. which is able to utilize both isomers. The crude enzyme catalyzed the dehalogenation of d- and l-2-chloropropionates to yield l- and d-isomers of lactate, respectively. The enzyme showed the same pH optimum and heat inactivation rate for the d- and l-isomers. Apparent K
m values for d- and l-2-chloropropionates were 4.5 and 1.0 mM, respectively. The enzyme acted specifically on 2-haloalkanoic acids. Activity staining of disc-gels electrophoresed witg the crude enzyme preparation showed that the dehalogenation of d- and l-2-chloropropionates, monochloroacetate, dichloroacetate, 2,2-dichloropropionate, and dl-2-chlorobutyrate is due to a single protein.Abbreviations MCA
monochloroacetic acid
- DCA
dichloroacetic acid
- TCA
trichloroacetic acid
- 2 MCPA
2-monochloropropionic acid
- 22 DCPA
2,2-dichloropropionic acid
- 3 MCPA
3-monochloropropionic acid
- 2 MCBA
2-monochlorobutyric acid
- 3 MCBA
3-monochlorobutyric acid
- 4 MCBA
4-monochlorobutyric acid 相似文献
3.
Huang H Yang P Luo H Tang H Shao N Yuan T Wang Y Bai Y Yao B 《Applied microbiology and biotechnology》2008,78(1):95-103
1,3-1,4-β-d-glucanase is an important endoglycosidase in the brewing and animal feed industries. To achieve high-level expression of
recombinant glucanase in Pichia pastoris, we designed sequences encoding the α-factor signal peptide from Saccharomyces cerevisiae and the truncated 1,3-1,4-β-d-glucanase from Fibrobacter succinogenes as a whole. The codons encoding the 52 amino acids of the signal peptide and 106 residues of the glucanase protein were optimized
for expression in P. pastoris; 189 nucleotides were changed. The G + C content was adjusted to 48–49%, and AT-rich stretches were eliminated to avoid premature
termination. The messenger ribonucleic acid secondary structure near the AUG start codon was also adjusted to ensure efficient
translation; the resulting glucanase production was twofold higher compared with that achieved with gene structure optimization
alone. We also propose a new fermentation strategy for the induction phase, in which 5/95% glycerol/methanol mixed feed was
used in days 1–3 and 100% methanol was used on days 4–6. By comparison with methanol feed and glycerol/methanol-mixed feed
alone, the yield of recombinant glucanase increased by 38.5 and 16.5%, respectively. The expressed optimized recombinant 1,3-1,4-β-d-glucanase constituted ~90% of the total secreted protein, reaching up to 3 g l−1 in the medium. 相似文献
4.
l-Ascorbic acid (AA) production in cells of Cyclotella cryptica Reimann, Lewin, Guillard (Bacillariophyceae) is enhanced when darkadapted cells are exposed to light.Heterotrophically grown cells incubated with d-[6-3H,6-14C]glucose and d-[1-3H,6-14C]glucose (2 h in dark followed by 15 h light) produced labeled AA with significantly different ratios of 3H and 14C. Comparisons of labeling patterns in AA and chitin-derived d-glucosamine support a path of conversion in Cyclotella from d-glucose to AA that inverts the carbon chain of the sugar. This process resembles similar conversions found in AA-synthesizing animals and species from two other algal classes.Abbreviations AA
l-Ascorbic acid
- glc
d-glucose
- glcN
d-glucosamine 相似文献
5.
Achromobacter xylosoxidans is known to utilize d-glucose via the modified Entner-Doudoroff pathway. Although d-gluconate dehydratase produced from this bacterium was purified and partially characterized previously, a gene that encodes
this enzyme has not yet been identified. To obtain protein information on bacterial d-gluconate dehydratase, we partially purified d-gluconate dehydratase in A. xylosoxidans and investigated its biochemical properties. Two degenerate primers were designed based on the N-terminal amino acid sequence
of the partially purified d-gluconate dehydratase. Through PCR performed using degenerate primers, a 1,782-bp DNA sequence encoding the A. xylosoxidans
d-gluconate dehydratase (gnaD) was obtained. The deduced amino acid sequence of A. xylosoxidans gnaD showed strong similarity with that of proteins belonging to the dihydroxy-acid dehydratase/phosphogluconate dehydratase family
(COG0129). This is in contrast to the archaeal d-gluconate dehydratase, which belongs to the enolase superfamily (COG4948). The phylogenetic tree showed that A. xylosoxidans
d-gluconate dehydratase is closer to the 6-phosphogluconate dehydratase than the dihydroxy-acid dehydratase. Interestingly,
a clade containing A. xylosoxidans enzyme was clustered with proteins annotated as a second and a third dihydroxy-acid dehydratase in the genomes of Clostridium acetobutylicum (Cac_ilvD2) and Streptomyces ceolicolor (Sco_ilvD2, Sco_ilvD3), indicating that the function of these enzymes is the dehydration of d-gluconate. 相似文献
6.
We demonstrate that 9-amino-NeuAc transferred to asialo-1-acid glycoprotein resists cleavage by bacterial, viral and mammalian sialidases. This is the first synthetic sialic acid analogue, which can be activated and transferred to glycoprotein, but is not a sialidase (EC 3.2.1.18) substrate.Abbreviations HPLC
high performance liquid chromatography
- BSA
bovine serum albumin
- NeuAc
N-acetyl-d-neuraminic acid, 5-acetamido-3,5-dideoxy-d-glycero-d-galacto-non-2-ulosonic acid
- 9-Amino-NeuAc
9-amino-5-N-acetyl-d-neuraminic acid, 5-acetamido-9-trideoxy-d-glycero-d-galacto-non-2-ulosonic acid
- CMP-NeuAc
cytidine-5-monophospho-N-acetyl-d-neuraminic acid
- CMP-9-amino-NeuAc
cytidine-5-monophospho-9-amino-5-N-acetyl-d-neuraminic acid
- 9-azido-NeuAc
5-acetamido-9-azido-3,5,9-trideoxy-d-glycero-d-galacto-non-2-ulosonic acid.
Enzymes EC 3.2.1.18
sialidase, acylneuraminylhydrolase
- EC 2.4.99.1
Galß1-4GlcNAc a(2-6)-sialytransferase 相似文献
7.
Syntheses of the following compounds are described: 6-(Trifluoroacetylamino)hexyl 2-acetamido-2,6-dideoxy--d-glucopyranoside and 2-acetamido-2-deoxy--d-xylopyranoside, two allyl 2-acetamido-2-deoxy--d-glucopyranosiduronic acid derivatives, and several allyl 2-acylamido-2-deoxy--d-glucopyranosides having different acyl groups. These and other compounds were used as inhibitors in the binding assay for the chicken hepatic lectin specific forN-acetylglucosamine. We found that: 1) The inhibitory potency ofN-acylglucosamine derivatives decreased progressively with increase in the size of acyl group, 2) absence of either 3-or 4-OH group ofN-acetylglucosamine lowered the binding affinity more than 100-fold, and 3) the presence of a negatively charged group (carboxylic acid) at the C-6 position did not lower the affinity. The first two items are similar to the mammalian hepatic galactose/N-acetylgalactosamine lectins, but the last item is in a strong contrast to the mammalian lectins.Abbreviations XyLNAc
N-acetyl-d-xylosamine
- BSA
bovine serum albumin
- NeuAc
N-acetylneuraminic acid
- GlcNAc34-BSA
amidino-type neoglycoprotein [6] containing on the average 34N-acetylglucosaminyl residues per BSA molecule 相似文献
8.
A. Yokota M. Rodriguez Y. Yamada K. Imai D. Borowiak H. Mayer 《Archives of microbiology》1987,149(2):106-111
Lipopolysaccharides were isolated from two strains of Thiobacillus ferrooxidans and one strain each of Thiobacillus thiooxidans, Thiobacillus novellus and Thiobacillus sp. IFO 14570. Neutral sugars, 2-keto-3-deoxyoctonate, fatty acids and the rare 2,3-diamino-2,3-dideoxyglucose were detected in all lipopolysaccharides. Lipopolysaccharides of both T. ferrooxidans strains contained l-glycero-d-manno-heptose, whereas that of T. thiooxidans contained both l-glycero-d-manno-heptose and d-glycero-d-manno-heptose. On the other hand, heptoses were absent in lipopolysaccharides of T. novellus and Thiobacillus sp. IFO 14570. Lipid A of T. ferrooxidans and T. thiooxidans contained both glucosamine and 2,3-diamino-2,3-dideoxyglucose, in contrast, lipid A of T. novellus and the Thiobacillus sp. IFO 14570 most likely contain only 2,3-diamino-2,3-dideoxyglucose as backbone sugar. Deoxycholate polyacrylamide gel electrophoresis revealed S-type character for all lipopolysaccharides studied. The significance of the lipopolysaccharide composition for taxonomic and phylogenetic questions with regard to thiobacilli is discussed.Abbreviations DAG
2,3-diamino-2,3-dideoxyglucose
- DOC
sodium deoxycholate
- GC
gas-liquid chromatography
- GC/MS
gas-liquid chromatography/mass spectrometry
-
d,d-Heptose
d-glycero-d-manno-heptose
-
l,d-Heptose
l-glycero-d-manno-heptose
- KDO
2-keto-3-deoxyoctonate
- LPS
lipopolysaccharide
- 3-OH-14:0
3-hydroxy-tetradecanoic acid
- PAGE
polyacrylamide gel electrophoresis
- PCP
phenol-chloroform-petroleum ether 相似文献
9.
Bernard Priem Julien Solokwan Jean-Michel Wieruszeski Gérard Strecker Hassan Nazih Henri Morvan 《Glycoconjugate journal》1990,7(2):121-132
The oligosaccharides Man5GlcNAc and Man3(Xyl)GlcNAc(Fuc)GlcNAc presumed to originate fromN-glycosyl proteins have been purified from an extracellular medium (concentration: 2–5 mg/l of 14 day cultures) of white campion (Silene alba) suspension culture. Their primary structures have been determined by1H-400-MHz NMR spectroscopy and FAB-MS spectrometry. They are probably the result of an autophagic process including protein catabolism due to sucrose starvation. Additional identification of digalactosylglycerol (galactolipid breakdown) argues for this hypothesis.Abbreviations Fuc
l-fucose
- Man
d-mannose
- Xyl
d-xylose
- GlcNAc
N-acetyl-d-glucosamine
- Gal
d-galactose
- Glc
d-glucose
- FAB-MS
fast atom bombardment mass spectrometry
- NMR
nuclear magnetic resonance 相似文献
10.
Gérard Strecker Jean-Michel Wieruszeski Claude Martel Jean Montreuil 《Glycoconjugate journal》1987,4(4):329-337
Alkaline borohydride reductive cleavage of hen ovomucin resulted in the release of a series of neutral and acidic oligosaccharide-alditols.1H-NMR spectroscopy in combination with fast ion bombardment-mass spectrometry in negative ion mode were used for investigation of the structures of three oligosaccharide-alditols. The following structures were established:
Abbreviations NeuAc
N-acetyl-d-neuraminic acid
- Gal
d-galactose
- GlcNAc
N-acetyl-d-glucosamine
- Gal-NAc-ol
N-acetyl-d-galactosaminitol
- NMR
nuclear magnetic resonance
- FAB-MS
fast atom bombardmentmass spectrometry 相似文献
11.
The chemical constitutional analysis of the lipopolysaccharide (LPS) isolated from Providencia rettgeri was carried out. Polyacrylamide gel electrophoresis using sodium dodecylsulfate or sodium deoxycholate showed that the lipopolysaccharide mostly consisted of short sugar chains. The lipid A was precipitated out after mild acid hydrolysis of LPS. From the supernatant degraded polysaccharide and unsubstituted core fractions were isolated. Compositional analysis of the core material revealed the presence of galacturonic acid, galactose, glucose, glucosamine, l-glycero-d-manno-heptose, 3-deoxy-d-manno-octulosonic acid, alanine and phosphorus. Methylation analysis of the core material indicated the presence of terminal units of glucose, galacturonic acid and glucosamine. The chemical structure of the lipid A was elucidated. It constitutes a -1,6-glucosamine disaccharide substituted on either side by ester and glycosidically-bond phosphate residues. The ester-bound phosphate was found to be substituted by a 4-amino-4-deoxy-l-arabinosyl residue. The amino groups of the backbone disaccharide are N-acylated by 3-O-(14:0)14:0 and 3-O-14:0.Two hydroxyl groups of the disaccharide are esterified by 3-O-(14:0)14:0 and 3-O-14:0. The taxonomical importance of these structural details will be discussed.Abbreviations LPS
lipopolysaccharide
-
l-d-heptose
l-glycero-d-manno-heptose
- dOclA
3-deoxy-d-manno-octulosonic acid
- DOC
sodium deoxycholate
- PAGE
polyacrylamide gel electrophoresis
- PS
degraded polysaccharide
- glc-ms
combined gas liquid chromatography-mass spectrometry 相似文献
12.
M. Zahr B. Fobel H. Mayer J. F. Imhoff V. Campos J. Weckesser 《Archives of microbiology》1992,157(6):499-504
Lipopolysaccharides were isolated from the moderate halophilic Ectothiorhodospira shaposhnikovii slight to and Ectothiorhodospira mobilis and from the extremely halophilic Ectothiorhodospira halophila by the hot phenol-water and purified by the phenol-chloroform-petroleum ether methods. The isolated lipopolysaccharides of all three species contained 3-deoxy-d-manno-octulosonic acid and d-glycero-d-mannoheptose indicating the existence of a core. They contained additionally glucose and uronic acids (E. shaposhnikovii and E. mobilis) or glucose, uronic acids and threonine (E. halophila). Sodium deoxycholate gel-electrophoresis of the three lipopolysaccharides, each showing only one major band, indicated R-type character of the lipopolysaccharides of the three Ectothiorhodospira species.The lipid A fractions of the lipopolysaccharides from E. shaposhnikovii and E. mobilis represented phosphorylated mixed lipid A types with both 2,3-diamino-2,3-dideoxy-d-glucose and d-glucosamine. The lipid A from E. halophila contained also phosphate and 2,3-diamino-2,3-dideoxy-d-glucose but only traces of d-glucosamine, which would indicated lipid ADAG. The fatty acid spectra were characterized by amide-bound 3-OH-10:0 and 3-OH-12:0 (E. shaposhnikovii), 3-OH-10:0 (E. mobilis), or 3-OH-10:0,3-OH-14:0, and 3-oxo-14-0 (E. halophila). The predominant ester-bound fatty acids were 14:0 and 16:0 (E. shaposhnikovii and E. mobilis), or 12:0 and 14:1 (E. halophila).Abbreviations DAG
2,3-diamino-2,3-dideoxy-d-glucose
- Kdo
3-deoxy-d-manno-octulosonic acid
- GlcA
glucuronic acid
- GalA
galacturonic acid
- GC-MS
combined gas liquid chromatographymass spectrometry
- GlcN
Glucosamine
- DOC
sodium deoxycholate
- LPS
lipopolysaccharide
- PAGE
polyacrylamide gel electrophoresis
- PCP
phenol-chloroform-petroleum ether 相似文献
13.
Rudrapatnam N. Tharanathan Akira Yokota Heike Rau Hubert Mayer 《Archives of microbiology》1993,159(5):445-452
Lipopolysaccharides (LPS), isolated from four Mycoplana species, i.e. the type strains of M. bullata, M. segnis, M. ramosa and M. dimorpha, were characterized onto their chemical composition and their respective lipid A-types. Those of M. bullata and M. segnis showed on DOC-PAGE an R-type character and had lipid A's of the Lipid ADAG-type which exclusively contained 2,3-diamino-2,3-dideoxy-d-glucose as lipid A sugar. LPS's of M. ramosa and M. dimorpha showed, although only weakly expressed, ladder-like patterns on DOC-PAGE indicating some S-type LPS's and lipid A of the d-glucosamine type (Lipid AGlcN). M. bullata LPS contained mannose and glucose in major amounts and additionally l-glycero-d-mannoheptose, whereas M. segnis LPS was composed of rhamnose, mannose and glucose together with both, d-glycero-d-manno- and l-glycero-d-manno-heptoses in a molar ratio of 1:2. All LPS's contained 2-keto-3-deoxy-octonic acid (Kdo), phosphate and an unidentified acidic component X. In addition to X, M. segnis LPS contained glucuronic and galacturonic acids, whereas M. ramosa LPS contained only galacturonic acid. Acetic acid hydrolysis of the LPS resulted in splitting off lipid A moieties, very rich in 3-hydroxy fatty acids, in particular in 3-OH-12:0 (in Lipid ADAG), or in 3-OH-14:0 (in Lipid AGlcN). Analysis of the 3-acyloxyacyl residues revealed major amounts of amide-linked 3-OH(3-OH-13:0)12:0 in lipid A of M. bullata and 3-OH(12:0)12:0 in lipid A of M. segnis. The rare 4-oxo-myristic acid (4-oxo-14:0) was observed only in M. bullata LPS, where it is ester-linked. Amide linked diesters could not be traced in M. ramosa and M. dimorpha. All four lipid A's lacked erster-bound acyloxyacyl residues.Non-standard abbreviations DAG
2,3-diamino-2,3-dideoxy-d-glucose
- Kdo
2-keto-3-deoxy-octonate
- LPS
lipopolysaccharide
- PITC
phenyl isothiocyanate
- NANA
N-acetyl neuraminic acid 相似文献
14.
We previously isolated and characterized a new free amino acid withd-configuration at the α-carbon,trans-3, 4-dehydro-d-2-aminopimelic acid and its related amino acids,d-2-aminopimelic acid and 4-hydroxy-l-2-aminopimelic acid fromAsplenium unilaterale. In this paper, we report that the biosynthetic relationshps among these three amino acids were studied using14C-and3H-labeled compounds as tracers. Glutamate and aspartate were shown to be good precursors and it was suggested that 4-hydroxy-l-2-aminopimelic acid is biosynthesized first and the twod-amino acids are derived from it. Furthermore, the distribution patterns of these non-protein amino acids inAsplenium sect.Hymenasplenium were examined in detail and they were evaluated by their biosynthetic pathway. Morphological characters especially on their
rhizomes were also examined and their character phylogeny was determined by outgroup comparison. Taking all the characters
available into account, the phylogenetic relationship among 7 species ofAsplenium sect.Hymenasplenium in Japan and Taiwan is discussed by the transformed cladistic method. 相似文献
15.
Lipopolysaccharides (LPS) were extracted by hot phenol-water from five strains each of Azospirillum lipoferum and Azospirillum brasilense. Rhamnose, glucose, glucosamine and 3-deoxy-d-mannooctulosonic acid were comon sugar constituents of all LPS preparations. 2-O-Mefucose, 3-O-Me-fucose, 3-O-Me-rhamnose and 2-O-Megalactose were found in LPSs of some A. brasilense strains. Fatty acid spectra from all LPSs studied were almost identical with predominance of 3-hydroxymyristic and 3-hydroxypalmitic acids. 3-Hydroxypalmitic acid was the only amide-linked fatty acid. Lipopolysaccharides isolated from A. brasilense showed higher heterogeneity in sugar composition than those from A. lipoferum.Abbreviations glc
gas liquid chromatography
- ms
mass spectrometry
- LPS
lipopolysaccharide
- dOclA
3-deoxy-d-mannooctulosonic acid
- 3-OH-16:0
3-hydroxypalmitic acid
- nir-
nitrite reductase negative
- nir+
nitrite reductase positive 相似文献
16.
Alexander Fosså Andreas Beyer Edith Pfitzner Bettina Wenzel Wolf -H. Kunau 《Molecular & general genetics : MGG》1995,247(1):95-104
We present the molecular cloning and sequencing of genomic and cDNA clones of the fox-2 gene of Neurospora crassa, encoding the multifunctional -oxidation protein (MFP). The coding region of the fox-2 gene is interrupted by three introns, one of which appears to be inefficiently spliced out. The encoded protein comprises 894 amino acid residues and exhibits 45% and 47% sequence identity with the MFPs of Candida tropicalis and Saccharomyces cerevisiae, respectively. Sequence analysis identifies three regions of the fungal MFPs that are highly conserved. These regions are separated by two segments that resemble linkers between domains of other MFPs, suggesting a three-domain structure. The first and second conserved regions of each MFP are homologous to each other and to members of the short-chain alcohol dehydrogenase family. We discuss these homologies in view of recent findings that fungal MFPs contain enoyl-CoA hydratase 2 and d-3-hydroxyacyl-CoA dehydrogenase activities, converting trans-2-enoyl-CoA via d-3-hydroxyacyl-CoA to 3-ketoacyl-CoA. In contrast to its counterparts in yeasts, the Neurospora MFP does not have a C-terminal sequence resembling the SKL motif involved in protein targeting to microbodies.The first two authors have contributed equally to this paperThe nucleotide sequence reported in this paper has been submitted to the GenBank/EMBL Data Bank with accession number 80052 相似文献
17.
The sialic acid analogue,N-acetyl-4-deoxy-neuraminic acid, is readily activated by CMP-sialic acid synthase from bovine brain. We also show that sialyl-transfer from CMP-N-acetyl-4-deoxy-neuraminic acid to asialo-
1-acid glycoprotein is achieved at a high rate using Gal1-4GlcNAc (2.6)-sialyltransferase from rat liver.In contrast toVibrio cholerae sialidase, fowl plague virus sialidase liberates boundN-acetyl-4-deoxy-neuraminic acid from the glycoprotein. Thus, as opposed to the general view, the action of neither synthase nor transferase depends on the presence of the hydroxy group at C-4 ofN-acetylneuraminic acid.Abbrevations BSA
bovine serum albumin
- DTE
dithioerythritol
- HPLC
high performance liquid chromatography
- NeuAc
N-acetyl-d-neuraminic acid
- 4-deoxy-NeuAc
N-acetyl-4-deoxy-d-neuraminic acid
- 4-epi-NeuAc
4-acetamido-3,5-dideoxy-d-glycero-d-talononulosonic acid
- CMP-NeuAc
Cytidine-5-monophospho-N-acetylneuraminic acid
- CMP-4-deoxy-NeuAc
Cytidine-5-monophospho-N-acetyl-4-deoxy-neuraminic acid
- FPV-sialidase
Fowl plague virus sialidase
- VCN
Vibrio cholerae neuraminidase 相似文献
18.
Glucuronoyl esterase is a novel carbohydrate esterase recently discovered in the cellulolytic system of the wood-rotting fungus
Schizophyllum commune on the basis of its ability to hydrolyze methyl ester of 4-O-methyl-d-glucuronic acid. This substrate was not fully corresponding to the anticipated function of the enzyme to hydrolyze esters
between xylan-bound 4-O-methyl-d-glucuronic acid and lignin alcohols occurring in plant cell walls. In this work we showed that the enzyme was capable of
hydrolyzing two synthetic compounds that mimic the ester linkages described in lignin-carbohydrate complexes, esters of 4-O-methyl-d-glucuronic and d-glucuronic acid with 3-(4-methoxyphenyl)propyl alcohol. A comparison of kinetics of hydrolysis of methyl and 3-(4-methoxyphenyl)propyl
esters indicated that the glucuronoyl esterase recognizes the uronic acid part of the substrates better than the alcohol type.
The catalytic efficiency of the enzyme was much higher with the ester of 4-O-methyl-d-glucuronic acid than with that of d-glucuronic acid. Examination of the action of glucuronoyl esterase on a series of methyl esters of 4-O-methyl-d-glucopyranuronosyl residues α-1,2-linked to xylose and several xylooligosaccharides suggested that the rate of deesterification
is independent of the character of the carbohydrate part glycosylated by the 4-O-methyl-d-glucuronic acid. 相似文献
19.
The plasma membrane-associated proteoglycans of a malignant human breast cell line (MDA-MB-231) were compared with the corresponding proteoglycans from a normal cell line (HBL-100). The labeled proteoglycans were isolated from the plasma membranes of cells grown in the presence of [3H]glucosamine and [35S]Na2SO4 by extraction with guanidine hydrochloride and subsequently purified by DEAE-ion exchange chromatography. Their structural properties were established by treatment with nitrous acid, heparitinase and chondroitinase ABC, and by gel filtration before and after alkaline -elimination. About 18% of the proteoglycans synthesized by these cell lines were associated with the plasma membranes. The HBL plasma membranes contained 80% heparan sulfate and 20% chondroitin sulfate proteoglycans whereas MDA plasma membranes had 50% heparan sulfate and 50% chondroitin sulfate proteoglycans. The MDA plasma membrane contained two heparan sulfate proteoglycans, both having nearly the same molecular size as the two species secreted into the medium by these cells. The HBL plasma membrane also contained two hydrodynamic size heparan sulfate proteoglycans. The larger hydrodynamic size species has a slightly lower molecular size than that secreted into the medium, and the smaller hydrodynamic size species was not detectable in the medium. Even though the major chondroitin sulfate proteoglycans from MDA plasma membranes were smaller in size than those from HBL plasma membrane, a larger proportion of the glycosaminoglycan chains of the former were bigger than those from the latter.Abbreviations CHAPS
3-[(3-cholamidopropyl)dimethylammonio]propane-1-sulfonate
- Di-OS
2-acetamido-2-deoxy-3-O-(-d-gluco-4-ene-pyranosyluronic acid)-d-galactose
- Di-4S
2-acetamido-2-deoxy-3-O-(-d-gluco-4-ene-pyranosyluronic acid)-4-O-sulfo-d-galactose
- Di-6S
2-acetamido-2-deoxy-3-O-(-d-gluco-4-ene-pyranosyluronic acid)-6-O-sulfo-d-galactose
- Gdn-HCl
guanidine hydrochloride
- WGA
wheat germ agglutinin 相似文献
20.
In Nocardia sp. 239 d-phenylalanine is converted into l-phenylalanine by an inducible amino acid racemase. The further catabolism of this amino acid involves an NAD-dependent l-phenylalanine dehydrogenase. This enzyme was detected only in cells grown on l- or d-phenylalanine and in batch cultures highest activities were obtained at relatively low amino acid concentrations in the medium. The presence of additional carbon- or nitrogen sources invariably resulted in decreased enzyme levels. From experiments with phenylalanine-limited continuous cultures it appeared that the rate of synthesis of the enzyme increased with increasing growth rates. The regulation of phenylalanine dehydrogenase synthesis was studied in more detail during growth of the organism on mixtures of methanol and l-phenylalanine. Highest rates of l-phenylalanine dehydrogenase production were observed with increasing ratios of l-phenylalanine/methanol in the feed of chemostat cultures. Characteristic properties of the enzyme were investigated following its (partial) purification from l- and d-phenylalanine-grown cells. This resulted in the isolation of enzymes with identical properties. The native enzyme had a molecular weight of 42 000 and consisted of a single subunit; it showed activity with l-phenylalanine, phenylpyruvate, 4-hydroxyphenyl-pyruvate, indole-3-pyruvate and -ketoisocaproate, but not with imidazolepyruvate, d-phenylalanine and other l-amino acids tested. Maximum activities with phenylpyruvate (310 mol min-1 mg-1 of purified protein) were observed at pH 10 and 53°C. Sorbitol and glycerol stabilized the enzyme.Abbreviations RuMP
ribulose monophosphate
- HPS
hexulose-6-phosphate synthase
- HPT
hexulose-6-phosphate isomerase
- FPLC
fast protein liquid chromatography 相似文献