Optimum pH Control Mechanism for Porcine Pancreatic α-Amylase

We studied the substrate-dependence of pH activity of porcine pancreatic α-amylase by using a series of p-nitrophenyl maltooligosaccharides. The mechanism controlling the optimum pH of mammalian α-amylase involved the reception and recognition of a substrate component at some other substrate binding sites, in addition to those at subsite 5 that were reported previously [K. Ishikawa et al., Biochemistry, 32, 6259–6265 (1993)].