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How do enzymes called glycosidases break glycosidic bonds?

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A biochemical flowchart shows the metabolic pathways for carbohydrate utilization, including glycolysis, the pentose phosphate pathway, and the tricarboxylic acid (TCA) cycle. The diagram traces the conversion of glucose, fructose, and glycerol through various intermediates, leading to energy production, carbon dioxide release, and biosynthesis of amino acids and porphyrins. Key steps and branches are labeled, with colored boxes highlighting biosynthetic outputs. — Carbohydrate Pathways for the utilization of carbohydrates.

Glycosidases are a class of enzymes that function as hydrolases, meaning they catalyze the hydrolysis of the glycosidic bonds that link sugar units in carbohydrates.12

In this biochemical process, the enzyme facilitates the cleavage of the bond by incorporating a water molecule into the reaction. This mechanism is distinct from other enzymatic processes, such as those involving glycogen phosphorylase, which break similar bonds by adding phosphoric acid rather than water.32

More broadly, many enzymatic reactions—including those involving the breakdown of complex molecules—rely on acid-base catalysis. In these reactions, the enzyme acts as a catalyst by participating in the transfer of protons to or from the substrate. This process makes the substrate unstable or more reactive, allowing the chemical bond to be broken or rearranged while the enzyme itself remains unchanged and available for further catalytic cycles.45