Glucosidases

Glucosidases are enzymes that catalyze the hydrolysis of glycosidic bonds to release glucose or glucose-containing residues from glycosides, oligosaccharides, and polysaccharides. They act on both alpha- and beta-linked substrates and are found across bacteria, fungi, plants, and animals, including humans. Their activities support digestion, glycoprotein processing, and the turnover of glycoconjugates.

Classification of glucosidases typically follows the stereochemistry of the targeted bond: alpha-glucosidases and beta-glucosidases. Examples of human alpha-glucosidases include maltase (glucoamylase family) and isomaltase, which cleave alpha-1,4 and alpha-1,6 linkages, while beta-glucosidases such as glucocerebrosidase (GBA) act on beta-glucosidic bonds in glucosylceramide. Lysosomal acid alpha-glucosidase (GAA) degrades glycogen-derived alpha-glucose residues. In the secretory pathway, alpha-glucosidases I and II trim glucose units from N-linked glycoprotein precursors, aiding proper folding and maturation of glycoproteins.

In humans, glucosidases perform diverse roles: digestive hydrolysis of dietary carbohydrates, processing of N-linked glycans, and lysosomal degradation of glycoconjugates. Deficiencies in specific glucosidases lead to disorders such as Pompe disease (GAA deficiency) and Gaucher disease (GBA deficiency). Congenital sucrase–isomaltase deficiencies also reflect disruption of intestinal glucosidase activity, affecting carbohydrate absorption.

Industrial and biotechnological applications include production of glucose syrups from starch using microbial glucoamylases and the use of beta-glucosidases in biomass conversion and flavor development. Glucosidases are studied for their catalytic mechanisms, which often involve retaining or inverting stereochemistry with key acidic and nucleophilic residues.

Overall, glucosidases are essential enzymes in carbohydrate metabolism, digestive physiology, glycoprotein processing, and various applied fields.

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