ABOLISHMENT OF GLYCOSYLATION BY GLU308GL MUTATION IN HUMAN HEPATIC FLAVIN-CONTAINING MONOOXYGENASE 3 EXPRESSED BY BACULOVIRUS EXPRESSION VECTOR SYSTEM

초록

Flavin-containing monooxygenases(FMOs)are a family of mocrosomal drug-metabolizing enzymes and specifically,FMO3 is a major isoform found in human liver.Among several single nucleotide polymorphisms of FMO3 gene founs in Korean,Glu308Gly mutant form with diminished FMO activity and markdly different secondary structure is found frequently.As with other enzymes,FMO3 is subject to several poet-transcriptional modifications like glycosylation.When both types FMO3s(wild and mutant)were expressed in the baculovirus expression vector system(BEVS)supplemented with a membrane ordering agent like Pluronic F-68(PF-68),only the wild type FMO3 was found to be glycosylation.Although the expressed FMO3s had different mobility on SDS-PAGE,upon de-glycosylation of wild tupe FMO3 with endoglycosidase H,they had same mobility. Furthermore,when they were expressed in the BEVS without supplement of PF-68,they were not glycosylated and had the same mobility on SDS-PAGE.Our results indicate that the glutamate 308 residue in the wild type FMO3 may undergo O-glycosylation and may serve to protect the expressed FMO3 from degradation by proteases.