An active-site carboxyl group in liquefying alpha-amylase: specific chemical modification.

Bacillus amyloliquefaciens alpha-amylase activity is pH-dependent and the plot log (Vmax/Km) versus pH implicated a carboxyl group of aspartic acid/glutamic acid at the active site. Chemical modification of alpha-amylase with EDC confirmed this view. Further, analysis of inactivation kinetics showed that modification of a single carboxyl group led to complete loss of the enzymic activity.