Comparative studies of two alpha-amylases acting on two Sorghum hybrids starches(Montecillos hybrid 2 and 3)and their significant differences in their catalytic activities

摘要

Starchy substances constitute the major part of the human diet for most people in the world.a-Amylases are widely distributed enzymes that initiate the hydrolysis of starch into low molecular weight malto-dextrins.The effect of pH on the rate of hydrolysis of both sorghum(Montecillo 2 and 3)hybrids starches by industrial bacterial amylase(1BA)and Aspergillus oryzae a-amylase(AOA)was studied.This result suggests that both IBA and AOA a-amylases had slightly high affinity for soluble starch of sorghum Montecillo 3 and 1 hybrids,respectively.Using the structural information available,the theoretical pK_a values of its ionizable residues directly involved in the catalytic region were determined.Both our experimental data and prediction studies indicated that the average pK_a values are in good agreement.