Styrylpyrone biosynthesis in Polyporus hispidus: II. Enzymic hydroxylation of p-coumaric acid and bis-noryangonin

• Published in: Biochimica et biophysica acta Vol. 343; no. 1; pp. 148 - 155
• Main Authors: Nambudiri, A.M.D., Vance, C.P., Towers, G.H.N.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20.03.1974
• Subjects: Ascorbic Acid - pharmacology; Basidiomycota - cytology; Basidiomycota - enzymology; Chelating Agents - pharmacology; Chromatography, DEAE-Cellulose; Chromatography, Gel; Cinnamates; Cytosol - enzymology; Hydrogen-Ion Concentration; Kinetics; Mixed Function Oxygenases - isolation & purification; Mixed Function Oxygenases - metabolism; Molecular Weight; NAD - pharmacology; NADP - pharmacology; Oxidation-Reduction; Pigments, Biological; Pyrans - metabolism; Structure-Activity Relationship; Styrenes - metabolism; Subcellular Fractions - enzymology
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/0304-4165(74)90246-3

p-Coumaric acid hydroxylating enaymes have been purified from Polyporus hispidus. Most of the activity was localized in the soluble fraction. The hydroxylating system appeared to be a tyrosinase (monophenol, dihydroxyphenylalanine: oxygen oxidoreductase, EC 1.10.3.1) type, ehibiting both p-coumaric acid hydroxylase and caffeic oxidase activities in the initial stages of purification. Sephadex G-200 gel filtration, as a final step in the purification procedure, resulted in the isolation of two forms which were not intercinvertible and which differed in thier molecular weights (185 000 and 45 000). he low molecular weight fraction did not contain detectable caffeic acid oxidase activity but was identical in other respects to the high molecular weight fraction. Both forms of the enzyme also hydroxylated bis-noryangonin to give hispidin, the two activities appearing to be the functions of the same proteins. NADH, NADPH or ascorbate served as an electron donor for the hydroxylations, the reduced nicotinamide nucleotides being the most effective. The effects of metal-chelating agents and substrate analogs on the hydroxylase activity were also examined.