title: Simultaneous absolute quantification of 11 cytochrome P450 isoforms in human liver microsomes by liquid chromatography tandem mass spectrometry with in silico target peptide selection.
abstract: Cytochrome P450 (CYP) proteins are involved in the biological oxidation and reduction of xenobiotics, affecting the pharmacological efficiency of drugs. This study aimed to establish a method to simultaneously quantify 11 CYP isoforms by multiplexed-multiple reaction monitoring analysis with liquid chromatography tandem mass spectrometry and in silico peptide selection to clarify CYP isoform expression profiles in human liver tissue. CYP1A2, 2A6, and 2D6 target peptides were identified by shot-gun proteomic analysis, and those of other isoforms were selected by in silico peptide selection criteria. The established quantification method detected target peptides at 10  fmol, and the dynamic range of calibration curves was at least 500-fold. The quantification value of CYP1A2 in Supersomes was not significantly different between the established method and quantitative immunoblot analysis. The absolute protein expression levels of 11 CYP isoforms were determined from one pooled and 10 individual human liver microsomes. In the individual microsomes, CYP2C9 showed the highest protein expression level, and CYP1A2, 2A6, 2C19, and 3A4 protein expression exhibited more than a 20-fold difference among individuals. This highly sensitive and selective quantification method is a useful tool for the analysis of highly homologous CYP isoforms and the contribution made by each CYP isoform to drug metabolism.
authors.affiliation: Division of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Kawakami
authors.forename: Sumio
authors.initials: S
authors.lastname: Ohtsuki
authors.forename: Junichi
authors.initials: J
authors.lastname: Kamiie
authors.forename: Takashi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Takaaki
authors.initials: T
authors.lastname: Abe
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Terasaki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D019295:Computational Biology / Q000379:methods; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000378:metabolism*; D005103:Expert Systems; D005260:Female; D006801:Humans; D007527:Isoenzymes; D057230:Limit of Detection; D008297:Male; D008832:Microchemistry / Q000379:methods; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D008875:Middle Aged; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism*; D040901:Proteomics / Q000379:methods; D053719:Tandem Mass Spectrometry; D055815:Young Adult
chemical_list: D007527:Isoenzymes; D010446:Peptide Fragments; D003577:Cytochrome P-450 Enzyme System