Stabilization of Pig Kidney Cathepsin A by Sucrose and Chloride Ion, and Inhibition of the Enzyme Activity by Diisopropyl Fluorophosphate and Sulfhydryl Reagents

摘要

1. Cathepsin A, the enzyme which hydrolyzes carbobenzoxy-L-glutamyl-L-tyrosine, was obtained from pig kidney. The enzyme was labile after dialysis but was stabilized by the addition of sucrose or KC1. In the presence of both stabilizers, the enzyme was active between pH 3 and 6.2. The enzyme activity was inhibited by diisoprophyl fluorophosphate and sulfhydryl reagents such asp-chloromercuribenzoic acid (PCMB). The enzyme was not activated by cysteine but enzyme which had been treated with PCMB was reactivated by cysteine.3. The passible identity of cathepsin A and catheptic carboxypeptidase is discussed.The abbreviations used: CGT, carbobenzoxy-L-glut-amyl-L-tyrosine ; DFP, diisopropyl fluorophosphate; PCMB,p-chloromercuribenzoic acid.