title: Appearance of enzyme activities catalyzing conversion of sterigmatocystin to aflatoxin B1 in late-growth-phase Aspergillus parasiticus cultures.
abstract: Two activities involved in terminal pathway conversion of sterigmatocystin to aflatoxin B1 were isolated from an aflatoxin-nonproducing mutant of Aspergillus parasiticus (avn-1), and the time course of appearance of the activities in culture was determined. Subcellular fractionation of fungal mycelia resolved the two activities into a postmicrosomal activity which catalyzed conversion of sterigmatocystin to O-methylsterigmatocystin and a microsomal activity which converted O-methylsterigmatocystin to aflatoxin B1. The two activities were absent in 24-h-old cells, increased to optimum levels during the stationary phase, and then declined.
mesh_terms: D016604:Aflatoxin B1; D000348:Aflatoxins / Q000096:biosynthesis*; D001230:Aspergillus / Q000201:enzymology* / Q000235:genetics; D002384:Catalysis; D055598:Chemical Phenomena; D002621:Chemistry; D007700:Kinetics; D009154:Mutation; D013241:Sterigmatocystin / Q000378:metabolism*; D014966:Xanthenes / Q000378:metabolism*
chemical_list: D000348:Aflatoxins; D014966:Xanthenes; D013241:Sterigmatocystin; D016604:Aflatoxin B1