Correlation of the Sulfhydryl Group with the Essential Calcium in Bacillus subtilis Saccharifying α-Amylase

Abstract

Amino acid composition of Bacillus subtilis saccharifying α-amylase [EC 3.2.1.1] was determined. The results suggested that the protein has consisted of approximately 331 amino acid residues. On the basis of the amino acid composition, the molecular weight of the amylase was estimated to be 41,922. One cysteine residue was shown to be contained per mole of the enzyme as a masked state, which became reactive to the sulfhydryl reagents after inactivation with EDTA at 60°C and pH 8.0. Calcium and the sole sulfhydryl group seemed to be essential for the enzymatic activity. The peptide containing the essential sulfhydryl group was isolated from the peptic digest of the amylase and its constituent amino acids were preliminarily determined