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At least 703 records · Page 39Linked to original sources
PubMed1983

Substrate specificity of the human splenic non-specific soluble beta-glucosidase.

The soluble non-specific 4-methylumbelliferyl-beta-D-glucosidase, one of the three splenic groups previously reported [Maret, A., Salvayre, R., Nègre, A., and Douste-Blazy, L. (1981) Eur. J. Biochem. 115, 455-461], was partially purified by gel filtration and heat-inactivation (which inactivated the contaminating acid beta-galactosidase). Its substrate specificity was accurately demonstrated by comparing the enzymic properties towards each substrate and two-substrate mixed assays: 4-methylumbelliferyl beta-D-galactopyranoside, beta-D-glucopyranoside, beta-D-fucopyranoside, alpha-L-arabinopyranoside and beta-D-xylopyranoside (relative rates 100, 95, 70, 15, 5, respectively in the standard conditions used) were competitively hydrolysed. Information about the enzymic site was given by the effect of various substrate analogs: generally we observed a greater inhibition of beta-galactosidase activity than beta-glucosidase and beta-fucosidase activities. Moreover, p-nitrophenyl-beta-D-mannopyranoside showed a strong inhibitory effect on the three main activities of this enzyme, similar to D-glucono-1,5-lactone inhibition. A selective inhibition by Triton X-100 on beta-D-galactosidase activity and in a lesser degree on beta-D-fucosidase activity was discussed. The non-specific soluble beta-glucosidase from a Gaucher patient and from normal subjects showed identical properties. Thus this enzyme is not affected by the mutation in the Gaucher type I spleen.

Adult↗
PubMed1988

Purification and characterization of a beta-glucosidase from Evernia prunastri.

Intracellular beta-glucosidase from Evernia prunastri has been purified to homogeneity using anion exchange on DEAE-Sephadex A-50, and gel filtration chromatography on Sephadex G-100 and Sepharose 6B. The purified beta-glucosidase showed a single protein band on native electrophoresis and its isoelectric point was at pH 3.12. The molecular mass, calculated from its partition coefficient on the Sepharose 6B column, was 311 kDa, being composed of several subunits of 60 and 70 kDa. The highest activity of this enzyme was attained at pH 4.0 and 60 degrees C. The enzyme showed strong resistance to thermal inactivation. Its activation energy was about 15 kJ/mol. Cellobiose, salicin, and p-nitrophenyl beta-D-glucoside, but not carboxymethylcellulose, were hydrolyzed by the enzyme, following substrate inhibition kinetics. The purified beta-glucosidase was considered a true cellobiase because of its great affinity towards cellobiose. Cellobiose inhibition does not seem to be a physiological phenomenon. Glucose inhibited enzyme activity in a competitive way (Ki = 1.26 mM). Fe3+ and Co2+ inhibited activity notably. Hg2+, Cu2+ and EDTA were practically ineffective. Even 200 mM gluconolactone did not affect enzyme activity.

Ascomycota↗
PubMed1985

beta-Glucosidase and beta-galactosidase in primary cultures of rat astrocytes: comparison to the brain enzymes.

In primary astrocyte cultures beta-glucosidase (EC 3.2.1.21) and beta-galactosidase (EC 3.2.1.23) showed pH optima and Km values identical to rat brain enzymes, using methylumbelliferyl glycosides and labeled gluco- and galactocerebrosides as substrates. The activities of both glycosidases increased in culture up to 3-4 weeks. In rat brain only galactosidase increased; glucosidase activity declined between 12-20 days after birth. The specific activities were two- to sixfold higher in astrocyte cultures than in rat brain. These activities were not due to uptake of enzymes from the growth medium. Secretion of beta-galactosidase, but not beta-glucosidase nor acid phosphatase could be demonstrated. These results support the suggestion of a degradative function for astrocytes in the brain.

Animals↗
PubMed1985

Application of cross-linked carboxymethyl cellulose degradation by beta-glucosidase and vaginal microbes to toxic shock syndrome.

Eleven bacterial and two yeast strains, four of which were previously identified as having activity on a lightly cross-linked carboxymethyl cellulose (CLD-2) found in one type of superabsorbent tampon, were grown on a variety of substrates, most containing cellulosics. None produced detectable amounts of cellulases, but all elaborated beta-glucosidase. None of these 13 strains nor 3 commercially obtained beta-glucosidase preparations could hydrolyze CLD-2, although a commercial cellulase and two other bacterial preparations known to produce cellulases could. Based on these results, it appears that previous work suggesting that the degradation of CLD-2 by vaginal microbes and beta-glucosidase is implicated in the production by Staphylococcus aureus of toxin causing toxic shock syndrome must be reevaluated.

Bacteria↗
PubMed1988

Nucleotide sequences of Saccharomycopsis fibuligera genes for extracellular beta-glucosidases as expressed in Saccharomyces cerevisiae.

We isolated two genes for extracellular beta-glucosidase, BGL1 and BGL2, from the genomic library of the yeast Saccharomycopsis fibuligera. Gene products (BGLI and BGLII) were purified from the culture fluids of Saccharomyces cerevisiae transformed with BGL1 and BGL2, respectively. Molecular weights of BGLI and BGLII were estimated to be 220,000 and 200,000 by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The two beta-glucosidases showed the same enzymatic characteristics, such as thermo-denaturation kinetics and dependencies on pH and temperature, but quite different substrate specificities: BGLI hydrolyzed cellobiose efficiently, but BGLII did not. This result is consistent with the observation that the S. cerevisiae transformant carrying BGL1 fermented cellobiose to ethanol but the transformant carrying BGL2 did not. Southern blot analysis revealed that the two beta-glucosidase genes were derived from Saccharomycopsis fibuligera and that the nucleotide sequences of the two genes are closely related. The complete nucleotide sequences of the two genes were determined. BGL1 and BGL2 encode 876- and 880-amino-acid proteins which were shown to be highly similar to each other. The putative precursors begin with hydrophobic segments that presumably act as signal sequences for secretion. Amino acid analysis of the purified proteins confirmed that BGL1 and BGL2 encode BGLI and BGLII, respectively.

Amino Acid Sequence↗
PubMed1997

6-phospho-alpha-D-glucosidase from Fusobacterium mortiferum: cloning, expression, and assignment to family 4 of the glycosylhydrolases.

The Fusobacterium mortiferum malH gene, encoding 6-phospho-alpha-glucosidase (maltose 6-phosphate hydrolase; EC 3.2.1.122), has been isolated, characterized, and expressed in Escherichia coli. The relative molecular weight of the polypeptide encoded by malH (441 residues; Mr of 49,718) was in agreement with the estimated value (approximately 49,000) obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis for the enzyme purified from F. mortiferum. The N-terminal sequence of the MalH protein obtained by Edman degradation corresponded to the first 32 amino acids deduced from the malH sequence. The enzyme produced by the strain carrying the cloned malH gene cleaved [U-14C]maltose 6-phosphate to glucose 6-phosphate (Glc6P) and glucose. The substrate analogs p-nitrophenyl-alpha-D-glucopyranoside 6-phosphate (pNP alphaGlc6P) and 4-methylumbelliferyl-alpha-D-glucopyranoside 6-phosphate (4MU alphaGlc6P) were hydrolyzed to yield Glc6P and the yellow p-nitrophenolate and fluorescent 4-methylumbelliferyl aglycons, respectively. The 6-phospho-alpha-glucosidase expressed in E. coli (like the enzyme purified from F. mortiferum) required Fe2+, Mn2+, Co2+, or Ni2+ for activity and was inhibited in air. Synthesis of maltose 6-phosphate hydrolase from the cloned malH gene in E. coli was modulated by addition of various sugars to the growth medium. Computer-based analyses of MalH and its homologs revealed that the phospho-alpha-glucosidase from F. mortiferum belongs to the seven-member family 4 of the glycosylhydrolase superfamily. The cloned 2.2-kb Sau3AI DNA fragment from F. mortiferum contained a second partial open reading frame of 83 residues (designated malB) that was located immediately upstream of malH. The high degree of sequence identity of MalB with IIB(Glc)-like proteins of the phosphoenol pyruvate dependent:sugar phosphotransferase system suggests participation of MalB in translocation of maltose and related alpha-glucosides in F. mortiferum.

Amino Acid Sequence↗
PubMed1987

alpha-Glucosidase deficiency (Pompe's disease).

alpha-Glucosidase is deficient (less than 30% of control) in Pompe's disease, but the extent of the deficiency does not always correlate with the severity of the clinical symptoms. The defects that lead to a deficiency of alpha-glucosidase include synthesis of catalytically inactive protein, absence of mRNA for the enzyme, decreased synthesis of the precursor, lack of phosphorylation of the precursor, impaired conversion of the precursor to the mature enzyme and synthesis of unstable precursor. A single type of defect can lead to different clinical phenotypes. The precursor of alpha-glucosidase is present in the brush border of the polarized epithelial cells of small intestine and kidney and is secreted into urine.

Biological Transport↗
PubMed1983

Acid alpha-glucosidase from human heart.

An alpha-glucosidase maximally active at acid pH has been purified from human heart some 2,600-fold and its properties compared to a purified alpha-glucosidase from human liver. Molecular weight was evaluated using three different analytical procedures. The effect of various cations was determined. Thermal lability was evaluated using three different substrates. Affinity and hydrolysis velocity constants for maltose, glycogen and 4-methylumbelliferyl-alpha-D-glucose were determined for both preparations at optimal hydrogen ion concentration. Inhibition studies were carried out using the disaccharide turanose. From this study, we conclude there are no significant differences in molecular weight or kinetic properties between the cardiac and hepatic alpha-glucosidase enzymes.

Cations↗
PubMed1997

Molecular mechanism in alpha-glucosidase and glucoamylase.

The hydrolysis of glucosidic linkage catalyzed by every carbohydrate-hydrolase is a reaction in which the product retains (alpha-->alpha or beta-->beta) or inverts (alpha-->beta or beta-->alpha) the anomeric configuration of the substrate. alpha-Glucosidase and glucoamylase are essentially distinguished by releasing alpha-glucose and beta-glucose, respectively, from the common substrates having alpha-glucosidic linkage. The distinction in the substrate specificities of the two enzymes was explained by the subsite affinities in their active sites. The amino acid sequences of the regions containing the catalytic sites were compared in alpha-glucosidases and glucoamylases from various sources. alpha-Glucosidases were suggested to be grouped into two families by their primary structures. The catalytic reaction mechanisms of carbohydrate-hydrolases were discussed in the two significant models of a nucleophilic displacement mechanism and an oxocarbenium ion intermediate mechanism.

Amino Acid Sequence↗
PubMedDate not supplied

[Relationship between lectin, alpha-, beta-glucosidase, and beta-galactosidase activities of Azospirillum].

The activities of alpha-glucosidase, beta-glucosidase, and beta-galactosidase were studied during the isolation and purification of lectins from Azospirillum brasilense Sp7 and Azospirillum lipoferum 59b cells. These enzymatic activities were revealed in crude extracts of surface proteins, protein fraction precipitated with ammonium sulfate or ethanol-acetone mixture, and protein fraction obtained by gel filtration on Sephadex G-75. The distribution of the enzymes between different protein fractions varied among the azospirilla studied. The cofunction of the A. brasilense Sp7 lectin and beta-galactosidase on the cell surface is assumed. A strong interaction between the A. lipoferum 59b lectin and glucosidases was revealed. The lectin from A. lipoferum 59b may possess saccharolytic activity.

Azospirillum↗
PubMed1979

[Evaluation of urease and beta-glucosidase activity for the practical identification of mycobacteria (author's transl)].

The urease and the beta-glucosidase for the identification of the mycobacteria were evaluated using 1,019 strains received for reference purposes in this laboratory in 1978. We found that the urease test was useful in the differential identification of BCG which, contrary to Mycobacterium bovis, gave a strong positive reaction in 3 h. The test was also useful to discriminate M. scrofulaceum from pigmented strains of M. avium. The beta-glucosidase test discriminated between M. tuberculosis and M. bovis and was useful to distinguish the niacine-positive strains of M. africanum which were usually negative in this test. The beta-glucosidase test was particularly useful in the differential identification of M. fortuitum and M. chelonei. In this report, the frequency distribution of the species which were submitted to this laboratory in 1978 was also shown and the results obtained for each of the conventional test procedures was presented.

Glucosidases↗
PubMed1991

Laminarinase from Penicillium funiculosum and its role in release of beta-glucosidase.

An extracellular laminarinase (1----3)-beta-glucan glucohydrolase (EC 3.2.1.6) was purified from culture filtrates of Penicillium funiculosum. It was homogeneous on polyacrylamide gel electrophoresis in the presence and absence of sodium dodecyl sulfate. It had a Mr of 14,000 and isoelectric point of pH 4.2. The apparent Km value for lamimarinase was 8.3 mg/ml and Vmax was 8 mumol/min/mg. The distribution of beta-glucosidase activity in two different species of Penicillium showed that P. funiculosum had a higher ratio of extracellular to cell wall bound activity than Penicillium janthinellum. Treatment of mycelia of both species with NaCl, EDTA, Triton X-100, or proteolytic enzymes did not release the cell wall bound beta-glucosidase. Incubation of the mycelia with the laminarinase released 2-4 times more beta-glucosidase than the estimated cell bound activity in P. janthinellum and P. funiculosum.

Cell Wall↗
PubMed1988

Study of beta-glucosidase from Helix pomatia by active site-directed inhibitors.

This work describes the purification of a beta-glucosidase (beta-D-glucoside-glucohydrolase EC 3.2.1.21) from the digestive juice of Helix pomatia and the study of the enzyme's active site by using different reversible and irreversible inhibitors. The catalytic constants of arylglycosides and their pH-dependent variations have also been determined. The inhibition studies demonstrate that conduritol epoxides are irreversible inhibitors of beta-glucosidase from the digestive juice of H. pomatia, and that nojirimicin shows tight binding with glucosidase: the formation and dissociation of the enzyme-inhibitor complex (dissociation constant 1.1 mumol/1) required several minutes.

1-Deoxynojirimycin↗
PubMed1988

Isozyme polymorphism of beta-glucosidase in Aspergillus nidulans.

Electrophoretic analysis of the distribution of various electromorphs at different beta-glucosidase zones was carried out in natural populations of A. nidulans, the A. nidulans group, and various species belonging to the genus Aspergillus from diverse geographical areas of India. The data show the existence of three segregating zones for beta-glucosidase, designated beta-GluI, beta-GluII, and beta-GluIII. All three zones are present in wild isolates of A. nidulans, and only two, i.e., beta-GluI and beta-GluIII, in the A. nidulans group and beta-GluII and beta-GluIII in different species of Aspergillus except A. terreus, A. flavus, and A. brevipes, where only beta-GluIII is present. Overall nine electromorphs are observed at beta-GluI, three at beta-GluII, and six at beta-GluIII zones, respectively. It can be concluded that there may be three structural genes for beta-glucosidase coding the three polymorphic zones in A. nidulans.

Aspergillus↗
PubMed1978

[Extraction of acid alpha-glucosidase from human spleen].

An efficient method for isolation of acid alpha-glucosidase from human spleen is developed. The method involves chromatography of the enzyme on rho-aminophenyl-alpha-D-glucopyranoside covalently bound to CH-Sepharose 4B, with subsequent gel filtration on Sephadex G-200. The enzyme was homogeneous by the polyacrylamide gel electrophoresis data; it was purified about 1500-fold, as compared with the crude extract (the total yield 12.5%). Besides acid alpha-glucosidase, the preparations of alpha-L-fucosidase, alpha-D-galactosidase and beta-N-acetylglucosaminidase were isolated and purified 200-, 130- and 280-fold, respectively. The nature of interaction between acid alpha-glucosidase and immobilized rho-aminophenyl-alpha-glucopyranoside is discussed.

Chromatography, Gel↗
PubMed1978

[Similar distribution of the activities of neutral alpha-glucosidase (gamma-amylase) and glucose-6-phosphatase in subcellular fractions from rat and trout livers].

alpha-glucosidases are cellular enzymes, able to split the polysaccharides into glucose. In subcellular fractions from rat and trout hepatocytes, the distribution patterns of neutral alpha-glucosidase and of glucose-6-phosphatase appear to be very similar, i.e., closely linked to the endoplasmic reticulum, and are somewhat related to the particular glycogen. The data suggest a probable role of neutral alpha-glucosidase in cell physiology and in carbohydrates metabolism.

Amylases↗
PubMed1985

[Beta-glucosidases. Molecular bases of Gaucher's disease].

The first part of this review deals the biochemical data concerning human and mammalian beta-glucosidases. Glucosylceramide-beta-glucosidase and non-specific beta-glucosidase are characterized following their physical, functional, structural and genetical properties. The second part deals with the biochemical and pathophysiological data concerning the Gaucher disease.

Animals↗