The Structure and Function of Acid Proteases
I. Specific Inactivation of an Acid Protease from Rhizopus chinensis by Diazoacetyl-DL-norleucine Methyl Ester
1973 年 73 巻 1 号 p. 61-68
詳細
1973 年 73 巻 1 号 p. 61-68
1. An acid protease from Rhizopus chinensis was rapidly inactivated by reaction with diazoacetyl-DL-norleucine methyl ester in the presence of cupric acetate at pH 5.0 or 5.6 and at 14°. Cupric ions are essential for this reaction and the rate of inactivation became faster with increasing concentration of cupric ions.
2. The inactivation took place almost in parallel with the incorporation of the reagent and the completely inactivated enzyme contained one residue of norleucine per molecule. The incorporated norleucine residue was removed completely from the enzyme by treatment with hydroxylamine.
3. The inactivation was slowed down in the presence of a substrate analog, benzyloxycarbonylglycyl-DL-norleucine methyl ester.
4. These results show that an essential carboxyl group at the active site of the enzyme is specifically esterified by diazoacetyl-DL-norleucine methyl ester.
5. Pepstatin, a specific inhibitor of pepsin [EC 3. 4. 4. 1], also inhibited Rhiz. protease. The rate of reaction of the diazo inactivator with the enzyme was decreased in the presence of pepstatin. p-Bromophenacyl bromide, a specific inactivator of pepsin, did not inactivate this enzyme.
