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)

During studies of the nutritional utilization of pyridoxine 5'-beta-D-glucoside, a major form of vitamin B6 in plants, we detected two cytosolic beta-glucosidases in jejunal mucosa. As expected, one was broad specificity beta-glucosidase that hydrolyzed aryl beta-D-glycosides but not pyridoxine beta-D-glucoside. We also found a previously unknown enzyme, designated pyridoxine-beta-D-glucoside hydrolase, that efficiently hydrolyzed pyridoxine beta-D-glucoside. These were separated and purified as follows: broad specificity beta-glucosidase 1460-fold and pyridoxine-beta-D-glucoside hydrolase 36,500-fold. Purified pyridoxine-beta-D-glucoside hydrolase did not hydrolyze any of the aryl glycosides tested but did hydrolyze cellobiose and lactose. Pyridoxine-beta-D-glucoside hydrolase exhibited a pH optimum of 5.5 and apparent molecular mass of 130 kDa by SDS-polyacrylamide gel electrophoresis and 160 kDa by nondenaturing gel filtration, in contrast to 60 kDa for native and denatured broad specificity beta-glucosidase. Glucono-delta-lactone was a strong inhibitor of both enzymes. Ionic and nonionic detergents were inhibitory for each enzyme. Conduritol B epoxide, a potent inhibitor of lysosomal acid beta-glucosidase, inhibited pyridoxine-beta-D-glucoside hydrolase but not broad specificity beta-glucosidase, but both were inhibited by the mechanism-based inhibitor 2-deoxy-2-fluoro-beta-D-glucosyl fluoride. Our findings indicate major differences between these two cytosolic beta-glucosidases. Studies addressing the role of vitamin B6 nutrition in regulating the activity and its consequences regarding pyridoxine glucoside bioavailability are in progress.
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PMID:Cytosolic pyridoxine-beta-D-glucoside hydrolase from porcine jejunal mucosa. Purification, properties, and comparison with broad specificity beta-glucosidase. 940 96

Novel derivatives of the D-glucosidase inhibitor 2,5-dideoxy-2,5-imino-D-mannitol bearing lipophilic aliphatic or aromatic amides attached to C-1 have been found to inhibit beta-glucosidase from Agrobacterium sp. in the nanomolar range. One of them, a coumarin derivative, ranks amongst the most active compounds in the class of reversible glycosidase inhibitors of the iminoalditol type.
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PMID:Novel, lipophilic derivatives of 2,5-dideoxy-2,5-imino-D-mannitol (DMDP) are powerful beta-glucosidase inhibitors. 1132 90

This paper is concerned with the determination of rate constants characterizing the binding and release of a slow binding inhibitor to and from an enzyme, here almond beta-glucosidase. We demonstrate the inability of the conventional method to yield reliable rate constants when one or more of these is less than 1 x 10(-4) per second. Instead one must use the much more accurate fitting of rate constants of the set of simultaneous differential equations characterizing the kinetic model. This procedure has the added advantage, when properly used, that the rate constants found pertaining to the inhibitor are largely insensitive to the particular value used for the enzyme concentration; i.e., the same data set may be fitted using a range of enzyme concentrations with no change in the resulting parameters. Hence the method can be used when little is known about the enzyme, except for the value of K(m), which is readily determined. Also, we report the somewhat unexpected finding that the association rate constant for the substrate (4-nitrophenyl-beta-d-glucopyranoside) is about one-third of the value of the corresponding rate constant for the inhibitor. The method is used to determine rate constants at several temperatures for the strong, slow binding inhibitor 2-phenethylglucoimidazole 1, enabling us to compute standard thermodynamic functions. The identity of these functions with those of isofagomine (2) reported earlier leads us to argue that the two compounds share a common binding mechanism, involving the same groups, whereas the different stabilities of the enzyme-inhibitor complexes must reside in those parts of the molecules that are not identical.
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PMID:Accurate determination of rate constants of very slow, tight-binding competitive inhibitors by numerical solution of differential equations, independently of precise knowledge of the enzyme concentration. 1148 21

A range of new C-1 modified derivatives of the powerful glucosidase inhibitor 2,5-dideoxy-2,5-imino-D-mannitol has been synthesised and their biological activities probed with the beta-glucosidase from Agrobacterium sp. Ki values are compared with those of previously prepared close relatives. Findings suggest dramatic effects exerted by the aglycon binding site on substrate/inhibitor binding.
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PMID:Probing the aglycon binding site of a beta-glucosidase: a collection of C-1-modified 2,5-dideoxy-2,5-imino-D-mannitol derivatives and their structure-activity relationships as competitive inhibitors. 1518 33

Venom from the pupal endoparasitoid, Pimpla hypochondriaca has previously been shown to contain a mixture of biologically active molecules. Currently, P. hypochondriaca venom was examined for the presence of hydrolase activity. Six hydrolases were consistently detected using the API ZYM semiquantitative colourimetric kit. The main hydrolases detected were; acid phosphatase, beta-glucosidase, esterase, beta-galactosidase, esterase lipase, and lipase. The most rapid and intense colour reaction was detected for acid phosphatase. The pH optimum and the specific activity of venom acid phosphatase was determined using p-nitrophenol phosphate as a substrate and were 4.8 and 0.47 nmol p-nitrophenol/min/microg of venom protein, respectively. The acid phosphatase activity was inhibited in a dose dependent manner by sodium fluoride (IC(50) 4.2 x 10(-4) M), and by cocktail inhibitor 2 (CI 2). P. hypochondriaca venom has previously been shown to display potent cytotoxic activity towards Lacanobia oleracea haemocytes maintained in vitro. The contribution of acid phosphatase in venom to this cytotoxic activity was investigated by titrating venom against CI 2 prior to the addition of L. oleracea haemocytes. The results suggest that, despite the relatively high levels of acid phosphatase activity in venom, venom acid phosphatase plays no role in the antihaemocytic activity of P. hypochondriaca venom in vitro.
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PMID:Hydrolase activity in the venom of the pupal endoparasitic wasp, Pimpla hypochondriaca. 1593 65

An intra-cellular beta-glucosidase was purified to homogeneity by gel filtration, ion exchange chromatography and HPGPLC from mycelial extract of Termitomyces clypeatus in the presence of the glycosylation inhibitor 2-deoxy-d-glucose. CD spectroscopy demonstrated that the purified enzyme exhibited alpha-helical conformation. MALDI-TOF identified the enzyme's molecular weight as 6688Daltons, but SDS-PAGE and immunoblotting indicated that the enzyme formed aggregates. The enzyme also showed unique properties of co-aggregation with sucrase in the fungus. The enzyme showed around 80% stability up to 60 degrees C and residual activity was 80-100% between pH ranges 5-8. The enzyme had higher specific activity against p-nitrophenyl-d-glucopyranoside than cellobiose and HPLC showed that the enzyme possesses transglycosylation activity and synthesizes cello-oligosaccharides by addition of glucose. The enzyme will be useful in synthetic biology to produce complex bioactive glycosides and to avoid chemical hazards. This is the first report of a beta-glucosidase enzyme with such a low monomeric unit size.
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PMID:Purification and characterization of a thermostable intra-cellular beta-glucosidase with transglycosylation properties from filamentous fungus Termitomyces clypeatus. 2003

Generally less glycosylation or deglycosylation has a detrimental effect on enzyme activity and stability. Increased production and secretion of cellobiase was earlier obtained in the presence of the glycosylation inhibitor 2-deoxy-d-glucose in filamentous fungus Termitomyces clypeatus [Mukherjee, S.; Chowdhury, S.; Ghorai, S.; Pal, S.; Khowala, S. Biotechnol. Lett.2006, 28, 1773-1778]. In this study the enzyme was purified from the culture medium by ultrafiltration and gel-permeation, ion-exchange and high-performance liquid chromatography, and its catalytic activity was six times higher compared to the control enzyme. K(m) and V(max) of the purified enzyme were measured as 0.187 mM and 0.018 U mg(-1), respectively, using pNPG as the substrate. The enzyme had temperature and pH optima at 45 degrees C and pH 5.4, respectively, and retained full activity in a pH range of 5-8 and temperatures of 30-60 degrees C. Interestingly less glycosylated cellobiase was resistant towards proteolytic as well as endoglycosidase-H digestion and showed higher stability than native enzyme due to increased aggregation of the protein. The enzyme also showed higher specific activity in the presence of cellobiose and pNPG and less susceptibility towards salts and different chemical agents. The beta-glucosidase can be considered as a potentially useful enzyme in various food-processing, pharmaceutical and fermentation industries.
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PMID:Enhanced activity and stability of cellobiase (beta-glucosidase: EC 3.2.1.21) produced in the presence of 2-deoxy-D-glucose from the fungus Termitomyces clypeatus. 2038 76