title: Spectroscopic characterization of the acid-alkaline transition of a thermophilic cytochrome P450.
abstract: The spectroscopic properties of thermophilic cytochrome P450 from the thermoacidophilic crenarchaeon Sulfolobus tokodaii strain 7 (P450st) were investigated in acidic and basic solutions. The resting form of ferric-P450st in weakly-acidic and neutral solutions contained a thiolate/H₂O coordinated low-spin heme. Below pH 1.5, P450st underwent cleavage of the Fe-S bond and was converted into apo-P450st. Above pH 8, the acid-alkaline transition due to the deprotonation of the water ligand was observed. The produced thiolate/OH⁻-coordinated ferric-P450st was stable at room temperature. The pK(a) value of 8.7 for the transition reflects the protonation properties of the distal side of the heme.
authors.affiliation: Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
authors.forename: Shohei
authors.initials: S
authors.lastname: Hayakawa
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Matsumura
authors.forename: Nobuhumi
authors.initials: N
authors.lastname: Nakamura
authors.forename: Masafumi
authors.initials: M
authors.lastname: Yohda
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohno
mesh_terms: D001059:Apoproteins / Q000737:chemistry / Q000378:metabolism; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002942:Circular Dichroism; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D004795:Enzyme Stability; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010084:Oxidation-Reduction; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013053:Spectrophotometry; D016944:Sulfolobus / Q000201:enzymology* / Q000254:growth & development* / Q000378:metabolism
chemical_list: D001059:Apoproteins; D019843:Archaeal Proteins; D011994:Recombinant Proteins; D006418:Heme; D003577:Cytochrome P-450 Enzyme System