Accession Number : AD0618152

Title :   ISOPHENOXAZINE SYNTHASE APOENZYME FROM PYCNOPORUS COCCINEUS,

Corporate Author : NATIONAL RESEARCH COUNCIL OF CANADA HALIFAX (NOVA SCOTIA) ATLANTIC REGIONAL LAB

Personal Author(s) : Nair,P. M. ; Vining,L. C.

Report Date : 23 SEP 1964

Pagination or Media Count : 10

Abstract : A crystalline preparation of the apoenzyme of isophenoxazine synthase (2-aminophenol:O2 oxidoreductase) was obtained from Pycnoporus coccincus. The holoenzyme was reconstituted by addition of riboflavin 5'-phosphate and Mn(2+). Flavin-adenine dinucleotide did not serve as a cofactor. Conversion of o-aminophenol to 2-amino3H-isophenoxazin-3-one was stoichiometric and in the absence of Mn(2+) required approx. I mole of riboflavin 5'phosphate acted as a catalyst. Incubation of the enzyme with o-aminophenol generated thiol groups and also made the reaction susceptible to inhibition by sulfhydryl reagents. A variety of reducing substances repressed the activity of the enzyme; inhibition by ascorbic acid could be reversed by increasing the concentration of riboflavin 5'-phosphate and Mn(2+). The reaction was also inhibited by substrate at concentrations above 0.6 mM. (Author)

Descriptors :   (*FUNGI, ENZYMES), (*ENZYMES, FUNGI), (*OXIDOREDUCTASES, FUNGI), VITAMIN B COMPLEX, PHOSPHATES, MANGANESE, IONS, NUCLEOTIDES, AMINES, OXIDATION, PHENOLS, THIOLS, CANADA

Distribution Statement : APPROVED FOR PUBLIC RELEASE