[Mechanism of amylase action on glucoside starch bonds]. / O mekhanieme deistviia amilaz na liukozidnye sviazi krakhmala

ABSTRACT

Functional groups of glucoamylase and alpha-amylase from Asp. awamori, alpha-amylase from Asp. oryzae and alpha- and beta-amylases from barley malt are identified. Kinetic curves of the activity dependency on pH, values of ionization heats and photooxidative inactivation draw to the conclusion that carboxyl-imidazole system enters into the active site of the enzymes. A hypothetic mechanism of hydrolysis of alpha-1,4-glucoside bond in starch molecule by alpha- and beta-amylases and of alpha-1,4- and alpha-1,6-glucoside bonds by glucoamylase is given. A theory of induced correspondence of enzyme and substrate satisfactorily explains the specificity of the enzyme action and the cause of complete starch convertion into glucose under glucoamylase action and of terminal starch hydrolysis by alpha- and beta-amylases.