Synthetic analogs of the active site of cytochrome P-450cam characterization of thiolpeptide fragment-hemin complexes by optical and ESR spectrometries.
Thiol-containing penta (Leu-Ala-Cys-Ser-Leu) and nona (Leu-Ala-Cys-Ser-Leu-Ile-Glu-Ser-Leu) peptides corresponding to residues 132-136 and 132-140, respectively, of apo-P450 from Psuedomonas putida were synthesized to examine heme-binding by the enzymes in the oxidized (ferric) form. The peptide-hemin complexes prepared in solution were characterized by their optical and ESR spectra. In these complexes without nitrogenous ligands, no ferric complexes in the low-spin state were observed, suggesting that simultaneous axial coordination of Cys-134 (thiolate) and Ser-139 (hydroxyl) of apo-P450cam to the heme is unlikely to occur. In the presence of nitrogenous ligands, such as py, Im and MeIm, the resulting complexes were good models of apo-P450cam-nitrogenous ligand adducts in the low-spin ferric state retaining a thiolate-Fe(III)-nitrogen axial coordination mode, as judged by their spectral pattern as well as by crystal field analysis of ESR g-values.
Sakurai
H
H
Uchikubo
H
H
Yoshimura
T
T
Maeda
M
M
Kawasaki
K
K
D000595:Amino Acid Sequence; D001665:Binding Sites; D003545:Cysteine; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D006418:Heme / Q000378:metabolism*; D008024:Ligands; D009842:Oligopeptides / Q000378:metabolism*; D011549:Pseudomonas / Q000378:metabolism; D013053:Spectrophotometry / Q000379:methods
D008024:Ligands; D009842:Oligopeptides; D006418:Heme; D003577:Cytochrome P-450 Enzyme System; D003545:Cysteine