A Catalytic Amino Acid and Primary Structure of Active Site inAspevgillus nigerα-Glucosidase

A Historical Perspective for the Catalytic Reaction Mechanism of Glycosidase; So As to Bring about Breakthrough in Confusing Situation

“…Available inhibitors, 41,42) 2-deoxy-2-fluoro--D-glucopyranosyl fluoride, 43) 1,1-difluoroalkyl-glucoside, 44) and 5-fluoro--D-glucopyranosyl fluoride 45) regarded as substrate analogs, and conduritol B epoxide 46) as a different type of inhibitor, 47,48) have been synthesized as a novel class of enzyme-activated irreversible inhibitors, which are all mechanism-based inhibitors (suicide substrate). In mechanism-based inhibitors, 49) usually glycone analog specifically binds to a carboxylate group at the active site directly involved in the activity, and then the glycosidase is irreversibly inactivated.…”

“…In mechanism-based inhibitors, 49) usually glycone analog specifically binds to a carboxylate group at the active site directly involved in the activity, and then the glycosidase is irreversibly inactivated. The mechanism-based inactivation reaction for many -and -glucosidases [43][44][45][46][47][48][50][51][52] and -glucan glucohydrolases [53][54][55] have been examined using the inhibitors named above. Most of the substrate analogs directly modify a catalytic carboxylate of enzyme, but 1,1-difluoroalkyl-glucoside 44) is distinct from the modification reaction of the other analogs.…”

Catalytic Reaction Mechanism Based on α-Secondary Deuterium Isotope Effects in Hydrolysis of Trehalose by European Honeybee Trehalase

“…2-Deoxy-2-fluoro-glucosides, 1,1-difluoroalkyl-glucosides, and 5-fluoro--glucosyl fluoride are regarded as substrate analogs, and conduritol B epoxide, as an analog in the transition state. 57,58) In mechanism-base inhibition, 59) usually glycone analog binds to a carboxylate group in active site directly involved in the activity, and then the glycosidase is irreversibly inactivated. Mechanism-base inactivation reactions for many -and -glucosidases [54][55][56][57][58][60][61][62] and -glucan glucohydrolases [63][64][65] have been examined using the inhibitors mentioned above.…”

α-Glucosidase Mutant Catalyzes “α-Glycosynthase”-type Reaction

“…6) We reported that three acidic residues (Asp481, Glu484, Asp647) in Schizosaccharomyces pombe a-glucosidase (SPG) were essential for the hydrolytic reaction, 7) in which Asp481 was found to be a catalytic nucleophile. 7,8) To learn the functions of acidic residues, a series of analyses of mutant enzymes have been done in our laboratory. Recently, the glycosynthase-type reaction was observed in an Asp481Gly mutant of SPG (D481G).…”