Purification and some properties of cathepsin A of small molecular size from pig kidney.

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Description

Cathepsin A [EC 3. 4. 2. -] of small molecular size (cathepsin A, S) has been purified about 800-fold from pig kidney by procedures including chromatographies on DEAE-Sephadex, SP-Sephadex, and Sephadex G-150.<br> 1. The homogeneity of the purified enzyme was proved by ultracentrifugation and polyacrylamide gel elecrophoresis. The molecular weight (100, 000) and isoelectric point (pI=5.0) were estimated.<br> 2. The enzyme was remarkably stabilized by sucrose and KCI, and was most stable at pH 5-5.5 in the presence of both stabilizers. The enzyme had not only peptidase activity but also esterase and amidase activity; it was optimally active at pH 5.2 for peptide hydrolysis and at pH 8 for the hydrolysis of esters and amides.<br> 3. Diisopropyl fluorophosphate and iodoacetamide completely inhibited these three activities.<br> 4. The enzyme hydrolyzed various benzoyl- and benzyloxycarbonyl-dipeptides with neutral, acidic, and basic amino acids, and proline in the C-terminal position. The carboxypeptidase nature of the enzyme was proved by its action on an oligopeptide.<br> 5. Several enzymatic properties of cathepsin A, S were almost the same as those of cathepsin A of large molecular size (cathepsin A, L) and the crude homogenate.

Journal

  • J Biochem (Tokyo)

    J Biochem (Tokyo) 77 (4), 729-737, 1975

    The Japanese Biochemical Society

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