Structure and Function of D-Amino Acid Oxidase II. Terminal Structure and Amino Acid Composition of Hog Kidney D-Amino Acid Oxidase

Abstract

Gross structure of hog kidney D-amino acid oxidase [EG 1.4.3.3] has been characterized by analyzing both N- and G-terminal residues and amino acid composition. The enzyme has been found to be composed of two methionine chains and two FAD per 100,000 g., and to be fairly rich in tyrosine and tryptophan residues. The C-terminal residue of these methionine chains has been identified to be leucine from the results of hydrazinolysis and carboxypeptidase A digestion. The partial specific volume of the enzyme calculated from the amino acid composition was 0.73 ml./g. which fairly agreed with the value of 0.742 ml./g. of the enzyme-benzoate complex previously measured by the usual pycnometer method. The results presented here and in the previous paper were likely to suggest that the enzyme is made up of two identical polypeptide chains.