Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.21 (beta-glucosidase)
3,280 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A total of 32 strains of the family Leptospiraceae (23 strains of Leptospira interrogans, 6 strains of Leptospira biflexa, 2 strains of Leptonema and 1 strain of Leptospira parva) were examined for enzyme activities using 89 substrates (API ZYM system). More than 90% of the strains belonging to the family Leptospiraceae possessed strong activities of beta-D-galactosidase, beta-D-glucosidase and 5 esterases (C5, C6, C8, C9 and C10). More than 90% of the strains belonging to the genus Leptospira, except L. parva, had strong activities of L-lysine arylamidase and alpha-L-glutamate arylamidase. L. biflexa strains, except serovar andamana, were different from the other strains examined in that they possessed glycyl-glycine arylamidase, glycyl-phenylalanine arylamidase and L-tryptophan arylamidase. L. biflexa strains, except andamana, L. parva and Leptonema strains possessed strong activities of glycine arylamidase and leucyl-glycine arylamidase. Two strains of the genus Leptonema were different from the strains belonging to the genus Leptospira in that they possessed strong activities of beta-D-lactosidase. L. parva lacked alpha-D-galactosidase which other strains belonging to the family Leptospiraceae possessed. Dendrogram analysis revealed that strains belonging to the family Leptospiraceae were divided into 4 groups. The first group consisted of all strains belonging to L. interrogans and serovar andamana of L. biflexa; the second group consisted of the remaining 5 serovars of L. biflexa; the third group consisted of the genus Leptonema; and the fourth group consisted of only L. parva.
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PMID:Enzyme activities of the strains belonging to family Leptospiraceae detected by the API ZYM system. 289 26

Homogenates of liver from cases of hepatic cirrhosis due to alpha 1-antitrypsin deficiency (PiZZ) alcoholism were analyzed for their content of various lysosomal enzymes. Also determined were the specific activities of lactate dehydrogenase, glutamate-oxaloacetate transaminase, glutamate-pyruvate transaminase, and creatine phosphokinase in the extracts of liver from cases of both kinds of hepatic cirrhosis: all of these activities were within the range of control values. Similarly, the specific activities of the following lysosomal hydrolases were unremarkable: acid phosphatase, beta-mannosidase, beta-fucosidase, beta-glucuronidase and beta-glucosidase. Hexosaminidase specific activity was increased twofold in livers from the cases of cirrhosis due to alpha 1-antitrypsin deficiency. The specific activity of alpha-mannosidase (measured at pH 4.5) in homogenates of livers from PiZZ individuals with cirrhosis and those with alcoholic cirrhosis was increased two- to four-fold. Chromatography of the high-speed supernatant fraction from homogenates of livers of cirrhotic and noncirrhotic individuals on columns of DEAE-cellulose resolved alpha-mannosidase activity into two components: under the conditions employed, acid pH optimum (pH 4.5) alpha-mannosidase did not bind to the resin, whereas intermediate pH optimum (pH 5.5) alpha-mannosidase could be eluted with 0.1 mol/l NaCl. Liver from one case of (PiZZ) alpha 1-antitrypsin deficiency and emphysema, without demonstrable cirrhosis, was found to contain normal levels of both acid alpha-mannosidase and intermediate alpha-mannosidase. However, cases of cirrhosis due to alpha 1-antitrypsin deficiency contained twice as much acid alpha-mannosidase and only one third to one fourth as much intermediate alpha-mannosidase as controls. The deficiency in hepatic intermediate alpha-mannosidase was also observed in 5 of 5 cases of alcoholic cirrhosis.
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PMID:Altered alpha-mannosidase isoenzymes in the liver in hepatic cirrhosis. 697 51

The catalytic mechanism of the retaining beta-glucosidase (Abg) from Agrobacterium faecalis involves a double-displacement process in which an alpha-glucosyl-enzyme intermediate is formed with general acid catalytic assistance and then hydrolyzed with general base assistance. Glu170 was identified as an important residue, possibly the acid/base catalyst, on the basis of sequence alignments. This glutamate is conserved in almost all enzymes in family 1 of glycoside hydrolases. Detailed pre-steady-state and steady-state kinetic analyses of the mutant E170G suggested very strongly that Glu170 is the acid/base catalyst. First, kcat values were invariant with pH over the range of 5.0-9.0. Secondly, rates of formation of the glycosyl-enzyme, calculated from kcat/Km and k2, were similar to those of wild-type enzyme for substrates not requiring protonic assistance but dramatically reduced for those needing acid catalysis. Thirdly, addition of azide as a competitive nucleophile increased kcat values 100-300-fold for substrates whose rate-limiting step is deglycosylation, yielding beta-glucosyl azide, but had no effect on the wild-type enzyme. Other anionic nucleophiles had similar, but less dramatic effects. Previous results [Gebler, J.C., et al. (1995) 34, 14547-14553] had indicated that Tyr298F is important for catalysis. The kinetic consequences of the mutations in the double mutant E170G-Y298F are additive, resulting in a 10(6)-fold reduction in kcat values and allowing the accumulation of a stable (t1/2 > 7 h) glucosyl-enzyme intermediate. Thus, Glu170 and Tyr298 function independently, and a possible role for Tyr298 in modulating the pKa of the catalytic nucleophile is proposed.
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PMID:Identification of the acid/base catalyst in Agrobacterium faecalis beta-glucosidase by kinetic analysis of mutants. 757 61

The celB gene encoding the cellobiose-hydrolyzing enzyme beta-glucosidase from the hyperthermophilic archaeon Pyrococcus furiosus has been identified, cloned, and sequenced. The transcription and translation gene was overexpressed in Escherichia coli, resulting in high-level (up to 20% of total protein) production of beta-glucosidase that could be purified by a two-step purification procedure. The beta-glucosidase produced by E. coli had kinetic and stability properties similar to those of the beta-glucosidase purified from P. furiosus. The deduced amino acid sequence of CelB showed high similarity with those of beta-glycosidases that belong to glycosyl hydrolase family 1, implicating a conserved structure. Replacement of the conserved glutamate 372 in the P. furiosus beta-glucosidase by an aspartate or a glutamine led to a high reduction in specific activity (200- or 1,000-fold, respectively), indicating that this residue is the active site nucleophile involved in catalysis above 100 degrees C.
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PMID:Characterization of the celB gene coding for beta-glucosidase from the hyperthermophilic archaeon Pyrococcus furiosus and its expression and site-directed mutation in Escherichia coli. 852 16

Mutations enhancing the thermostability of beta-glucosidase A of Bacillus polymyxa, a family 1 glycosyl hydrolase, have been obtained after hydroxylamine mutagenesis of a plasmid containing the bglA gene, transformation of Escherichia coli with the mutagenized plasmid, and identification of transformant colonies that showed beta-glucosidase activity after a thermal treatment that inactivated the wild-type enzyme. Two additive mutations have been characterized that cause replacement of glutamate at position 96 by lysine and of methionine at position 416 by isoleucine respectively. The thermoresistant mutant enzymes showed increased resistance to other denaturing agents, such as pH and urea, while their kinetic parameters did not change. CD spectra indicated that the E96K replacement caused an increase in alpha-helix content. The observed effect of the M416I mutation is consistent with the lower content of cysteine and methionine found in family 1 enzymes of thermophilic species compared with similar ones from mesophilic organisms.
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PMID:Amino acid substitutions enhancing thermostability of Bacillus polymyxa beta-glucosidase A. 861 77

Glycosynthases are nucleophile mutants of retaining glycosidases that catalyze the glycosylation of sugar acceptors using glycosyl fluoride donors, thereby synthesizing oligosaccharides. The 'original' glycosynthase, derived from Agrobacterium sp. beta-glucosidase (Abg) by mutating the nucleophile glutamate to alanine (E358A), synthesizes oligosaccharides in yields exceeding 90% [Mackenzie, L.F., Wang, Q., Warren, R.A.J. and Withers, S.G. (1998) J. Am. Chem. Soc. 120, 5583-5584]. This mutant has now been re-cloned with a His(6)-tag into a pET-29b(+) vector, allowing gram scale production and single step chromatographic purification. A dramatic, 24-fold, improvement in synthetic rates has also been achieved by substituting the nucleophile with serine, resulting in improved product yields, reduced reaction times and an enhanced synthetic repertoire. Thus poor acceptors for Abg E358A, such as PNP-GlcNAc, are successfully glycosylated by E358S, allowing the synthesis of PNP-beta-LacNAc. The increased glycosylation activity of Abg E358S likely originates from a stabilizing interaction between the Ser hydroxyl group and the departing anomeric fluorine of the alpha-glycosyl fluoride.
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PMID:The E358S mutant of Agrobacterium sp. beta-glucosidase is a greatly improved glycosynthase. 1064 8

The gene encoding hydroxyisourate hydrolase, a novel ureide-metabolizing enzyme, has been cloned from soybean (Glycine max). The gene encodes a protein that is 560 amino acids in length and contains a 31-amino acid signal sequence at the N terminus that is not present in the mature protein. The presence of two SKL motifs near the C terminus suggests that the protein resides in the peroxisome. This expectation is borne out by results from immunogold electron microscopy, which revealed that hydroxyisourate hydrolase was localized in the peroxisomes of uninfected root nodules. The gene encoding hydroxyisourate hydrolase was expressed in Escherichia coli, and soluble, catalytically active enzyme was purified to homogeneity. Sequence analysis revealed considerable homology with members of the beta-glucosidase family of enzymes. Two glutamate residues, E199 and E408, align with the conserved glutamates that play catalytic roles in the beta-glucosidases. However, the other residues that have been identified by crystallography to interact directly with the substrates in beta-glucosidases are not conserved in hydroxyisourate hydrolase. The E199A and E408A hydroxyisourate hydrolase mutants were devoid of detectable catalytic activity. Analysis of transcripts for hydroxyisourate hydrolase demonstrated that its level of expression was highest in the nodule; mRNA was detectable 12 d after infection and increased until 21 d postinfection, then declined. In a similar manner, immunodetection of hydroxyisourate hydrolase indicated preferential localization in the nodule; the amount of protein detected was maximal at 21 d postinfection. The pattern of expression of hydroxyisourate hydrolase matched that of urate oxidase, and supports the hypothesis that hydroxyisourate hydrolase plays a role in ureide metabolism.
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PMID:Cloning and expression of the gene for soybean hydroxyisourate hydrolase. Localization and implications for function and mechanism. 1248 Oct 89

A putative bgl operon of Pectobacterium carotovorum subsp. carotovorum LY34 (Pcc LY34) was isolated. Sequence analysis of the 5,557 bp cloned DNA fragment (accession no. AY542524) showed three open reading frames (bglT, bglP, and bglB) predicted to encode 287, 633, and 468 amino acid proteins respectively. BglT and BglP ORFs show high similarity to that of the Pectobacterium chrysanthemi ArbG antiterminator and ArbF permease respectively. Also, the latter contains most residues important for phosphotransferase activity. The amino acid sequence of BglB showed high similarity to various beta-glucosidases and is a member of glycosyl hydrolase family 1. The purified BglB enzyme hydrolyzed salicin, arbutin, pNPG, and MUG. The molecular weight of the enzyme was estimated to be 53,000 Da by SDS-PAGE. The purified beta-glucosidase exhibited maximal activity at pH 7.0 and 40 degrees C, and its activity was enhanced in the presence of Mg(2+). Two glutamate residues (Glu(173) and Glu(362)) were found to be essential for enzyme activity.
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PMID:Analysis of bgl operon structure and characterization of beta-glucosidase from Pectobacterium carotovorum subsp. carotovorum LY34. 1556 64

An asc operon of Pectobacterium carotovorum subsp. carotovorum LY34 (Pcc LY34) was isolated from a genomic library in a screen for beta-glucosidase activities. Sequence analysis of the 5618-bp cloned DNA fragment (accession number AY622309) showed three open reading frames (ascG, ascF, and ascB) that are predicted to encode 375, 486, and 476 amino acid proteins, respectively. The AscG ORF shared a high similarity with the Escherichia coli AscG repressor. The AscF ORF shared 81% identity with the E. coli AscF PTS enzyme II(asc), while the AscB ORF was highly similar to 6-phospho-beta-glucosidases and is a member of the glycosyl hydrolase family 1. The purified AscB enzyme hydrolyzed salicin, arbutin, pNPG, and MUG. It exhibited maximal activity at pH 7.0 and 40 degrees C, and its activity was enhanced in the presence of Mg(2+) and Ca(2+). The molecular weight of the enzyme was estimated to be 53 000 Da by SDS-PAGE. Two conserved glutamate residues (Glu(182) and Glu(374)) were shown to be important for AscB activity.
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PMID:Structural and biochemical analysis of the asc operon encoding 6-phospho-beta-glucosidase in Pectobacterium carotovorum subsp. carotovorum LY34. 1574 78

Colletotrichum lindemuthianum was able to grow and produce extracellular cellulolytic activity in a defined medium containing cellulose as the main carbon substrate. As measured either by the hydrolysis of 4-methylumbelliferyl-beta-D -cellotrioside or the release of glucose from carboxymethylcellulose, activity reached a peak after 13 days of incubation and then declined whereas growth markedly increased afterwards. Detection of glucose in carboxymethylcellulose hydrolysates suggested the concerted operation of endo-1,4-beta-glucanase, cellobiohydrolase (exo-1,4-beta-glucanase) and beta-glucosidase activities. The highest levels of cellulolytic activity were obtained in media supplemented with cellulose and glutamate. Other carbon and nitrogen sources markedly influenced growth and enzyme production. Oligonucleotides homologous to specific regions of the cellobiohydrolase-encoding cbhII gene from Trichoderma reesei were used to isolate a C. lindemuthianum cbhII-DNA fragment whose sequence revealed homologies of 98% and 92% with the nucleotide and the deduced amino acid sequences of the corresponding cbhII-DNA of T. reesei, respectively. RT-PCR and Southern blot analyses of total RNA samples obtained from cellulose-grown but not from glucose-grown mycelium revealed the expression of the corresponding cbhII transcript. The cbhII-cDNA fragment was cloned and sequenced.
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PMID:Degradation of cellulose by the bean-pathogenic fungus Colletotrichum lindemuthianum. Production of extracellular cellulolytic enzymes by cellulose induction. 1592 83


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