ISOPHENOXAZINE SYNTHASE APOENZYME FROM PYCNOPORUS COCCINEUS,
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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 23, 1964
- Accession Number
- AD0618152
Entities
People
- L. C. Vining
- P. M. Nair
Organizations
- National Research Council Canada