Ostrich pancreatic α-amylase: Kinetic properties, amino terminal sequence and subsite structure

Abstract

Ostrich pancreatic α-amylase (OPA) was purified to homogeneity in the presence of protease inhibitors by a single-step affinity chromatography technique. The first 53 amino acids of the N-terminus were identified by gas-phase sequencing. From kinetic parameters (k_cat/K_m) a subsite profile was established leading to a five subsite model for OPA. The pK_a values of catalytic residues were determined as 5.75 and 8.36. Inhibition of OPA by monosaccharides, β-cyclodextrin and a wheat α-amylase inhibitor was studied.