B-D-Glucosidases

Brandt V, GeerUngs A, Tits M, Delaude C, Van der Heijden R, Verpoorte R, Angenot L. New strictosidine b-glucosidase from Strychnos mellodora. Plant Physiol. Biochem. 2000 38 187-192. GeerUngs A, Ibanez MM-L, MemeUnk J, Van der Heijden R, Verpoorte R. Molecular cloning and analysis of strictosidine b-D-glucosidase, an enzyme in terpenoid indole alkaloid biosynthesis in Catharanthus roseus. J. Biol. Chem. 2000 275 3051-3056. 

The type of intermediate that is formed in the slow inhibition with D-gly-cals was identified, with the aid of the ) -D-glucosidase A3 from Asp. wentii, as an ester of 2-deoxy-D-araA/ o-hexose with an aspartic acid side-chain. The same aspartoyl residue had already been shown, by labeling with con-duritol B epoxide (see Section 111,1), to be essential for -D-glucoside hydrolysis. In addition, this aspartate was found to form a glycosyl -enzyme... 

A. Nahrstedt, W. Hosel, and A. Walther, Phytochemistry, 18(1979) 1137-1141 Resistance of the /(-D-glucosidases of Refs. 151 and 152 against inactivation by conduritol B epoxide, W. H6sel, personal communication. 

A different type of reactive bromo compound having a moderate resemblance to hexoses is represented by the bromoconduritols B (40) and F (41), named after the respective parent tetrahydroxycyclohexene. Even thou their hydroxylation pattern resembles that of D-glucose, only a few examples of D-glucosidase inhibition have been reported. The first was a-D-glucosi-dase from yeast, which is inhibited by bromoconduritol B (formerly called bromoconduritol A), having ki(max)/Kj 69,000 M" min", by alkylation of a histidine residue at the active site. 

The only other examples of bromoconduritol inhibition reported so far are a cytosolic jff-D-glucosidase from calf liver and the lysosomal ff-D-glu-cosidase from calf spleen. In spite of the 6500-fold difference in their reactivity with conduritol B epoxide (see Table XI), both enzymes are rapidly inactivated by bromoconduritol F, with kj(max)/Kj 10 M min for the cytosolic enzyme and lq(max)/Ki 3.2 10 for the crude and 3.9 10 M min for the purified lysosomal enzyme. It should be noted that purification of the lysosomal jS-D-glucosidase had effects on the reactivity with bromoconduritol F similar to those it had on the reactivity with conduritol B epoxide (see Table XI). 

Shulman and coworkers showed that ) -D-glucosyl isothiocyanate (43) can be used for the specific inactivation of ) -D-glucosidase B from sweet... 

Figure 1. pH-dependence of the half-life for loss of activity in native and glutaraldehyde-modified j9-D-glucosidase upon preincubation at the indicated pH values and at a range of temperatures from 55o to 70 oC, with subsequent assay at pH 5.0, 45 oC. A,B Linear-ordinate and logarithmic-ordinate plots, respectively, for the glutaraldehyde-modified enzyme. 

D. E. Walker and B. Axelrod, Evidence for a single catalytic site on the P-d-glucosidase-P-D-galactosidase of almond emulsin, Arch. Biochem. Biophys., 187 (1978) 102-107. 

B. W. Sigurdskjold, B. Duus, and K. Bock, Hydrolysis of substrate analogues catalysed by P-D-glucosidase from Aspergillus niger. Part II Deoxy and deoxyhalo derivatives of cellobiose, Acta Chem. Scand., 45 (1991) 1032-1041. 

L. Sim, K. Jayakanthan, S. Mohan, R. Nasi, B. D. Johnston, B. M. Pinto, and D. R. Rose, New glucosidase inhibitors from ayurvedic herbal treatment for type 2 diabetes Structures and inhibition of human intestinal maltase-glucoamylase with compounds from Salacia reticulata, Biochemistry, 49... 

FlC. 1.—Relative Rates of Activity Against Glycosides at Various pH Values. [A. Hydrolysis of sucrose by /3-D-fructofuranosidase of Saccharomyces cerevisiae O, intact cells and A, toluene-treated cells (results of Wilkes and Palmer40). B. Maltose , fermentation by intact baker s yeast A, hydrolysis by a-D-glucosidase (results of Hestrin41 see also Ref. 42).]... 

Fig. 3. —Proposed Structure of a Portion of theHemieellulosicXyloglucan of the Primary Cell-Wall of Dicots (After Albersheim5-64). [Heptasac-charide A and nonasaccharide B are derived from oligosaccharide C by the action of endo-(l—>4)-/ -D-glucanase at the bonds indicated by arrows. Pentasaccharide D is derived from "B by the combined action of a-L-fucosidase, a-D-xylosidase, and /J-D-glucosidase. A = L-arabinopyranose F = L-fucose G = D-glucose Gal = D-galactose X = D-xylose.]...

Fig. 4 Time course of ectoprotease activities (EPA, pmoles l-1 h-1) (a, b), ccto-/(-glucosidase activities (EGA, nmoles l-1 h ) (c, d) and bacterial production (106 cells r1 h-1) (e, f) during 30 days incubation in low Fe (<1 nM Fe) bioassay and Fe-amended bioassay...

Adney, W. S., Baker, J. O., Vinzant, T. B., Thomas, S. R., and Himmel, M. E., Kinetic comparison of beta-D-glucosidases of industrial Importance. Abstracts of Papers of the American Chemical Society 1995, 209, 119-BTEC. 

Andrews, J S, Johnston, B D, Pinto, B M, Synthesis of a dithio analogue of n-propyl kojibioside as a potential glucosidase I inhibitor, Carbohydr. Res., 310, 27-33, 1998. 

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