title: X-ray absorption spectroscopic characterization of a cytochrome P450 compound II derivative.
abstract: The cytochrome P450 enzyme CYP119, its compound II derivative, and its nitrosyl complex were studied by iron K-edge x-ray absorption spectroscopy. The compound II derivative was prepared by reaction of the resting enzyme with peroxynitrite and had a lifetime of approximately 10 s at 23 degrees C. The CYP119 nitrosyl complex was prepared by reaction of the enzyme with nitrogen monoxide gas or with a nitrosyl donor and was stable at 23 degrees C for hours. Samples of CYP119 and its derivatives were studied by x-ray absorption spectroscopy at temperatures below 140 (K) at the Advanced Photon Source of Argonne National Laboratory. The x-ray absorption near-edge structure spectra displayed shifts in edge and pre-edge energies consistent with increasing effective positive charge on iron in the series native CYP119 < CYP119 nitrosyl complex < CYP119 compound II derivative. Extended x-ray absorption fine structure spectra were simulated with good fits for k = 12 A(-1) for native CYP119 and k = 13 A(-1) for both the nitrosyl complex and the compound II derivative. The important structural features for the compound II derivative were an iron-oxygen bond length of 1.82 A and an iron-sulfur bond length of 2.24 A, both of which indicate an iron-oxygen single bond in a ferryl-hydroxide, Fe(IV)OH, moiety.
authors.affiliation: Department of Chemistry, University of Illinois, 845 West Taylor Street, Chicago, IL 60607, USA. men@uic.edu
authors.forename: Martin
authors.initials: M
authors.lastname: Newcomb
authors.forename: James A
authors.initials: JA
authors.lastname: Halgrimson
authors.forename: John H
authors.initials: JH
authors.lastname: Horner
authors.forename: Erik C
authors.initials: EC
authors.lastname: Wasinger
authors.forename: Lin X
authors.initials: LX
authors.lastname: Chen
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Sligar
mesh_terms: D015502:Absorptiometry, Photon; D019843:Archaeal Proteins / Q000737:chemistry*; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D009569:Nitric Oxide / Q000737:chemistry; D030421:Peroxynitrous Acid / Q000737:chemistry; D011166:Porphyrins / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000737:chemistry*
chemical_list: D019843:Archaeal Proteins; D011166:Porphyrins; D017382:Reactive Oxygen Species; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D003577:Cytochrome P-450 Enzyme System; D007501:Iron; C408874:CYP119 protein, Sulfolobus solfataricus