title: Phenylalanine 445 within oxidosqualene-lanosterol cyclase from Saccharomyces cerevisiae influences C-Ring cyclization and deprotonation reactions.
abstract: [reaction: see text] We describe the Saccharomyces cerevisiae oxidosqualene-lanosterol cyclase Phe445 site-saturated mutants that generate truncated tricyclic and altered deprotonation product profiles. Among these mutants, only polar side-chain group substitutions genetically complemented yeast viability and produced spatially related product diversity, supporting the Johnson model that cation-pi interactions between a carbocationic intermediate and an enzyme can be replaced by an electrostatic or polar side chain to stabilize the cationic intermediate, but with product differentiation.
authors.affiliation: Department of Biological Science and Technology, National Chiao Tung University, 300, Hsin-Chu, Taiwan, Republic of China. tkwmll@mail.nctu.edu.tw
authors.forename: Tung-Kung
authors.initials: TK
authors.lastname: Wu
authors.forename: Yuan-Ting
authors.initials: YT
authors.lastname: Liu
authors.forename: Feng-Hsuan
authors.initials: FH
authors.lastname: Chiu
authors.forename: Cheng-Hsiang
authors.initials: CH
authors.lastname: Chang
mesh_terms: D000595:Amino Acid Sequence; D003500:Cyclization; D019751:Intramolecular Transferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D010649:Phenylalanine / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship
chemical_list: D010649:Phenylalanine; D019751:Intramolecular Transferases; C021924:lanosterol synthase