title: Identification of the ligand trans to thiolate in cytochrome P-450 LM2 by chemical modification.
abstract: About 3 tyrosine residues of cytochrome P-450 LM2 are accessible to chemical modification with tetranitromethane. Nitration of two tyrosines inactivates the enzyme to about 20%. The partial formation of a hyper-porphyrin spectrum originating from the pK shift by nitration and formation of a tyrosinate is prevented by modification in the presence of the inhibitor metyrapone. These findings support the assumption of a tyrosine residue as sixth ligand of the heme iron in cytochrome P-450 LM2.
mesh_terms: D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D008297:Male; D008697:Methane / Q000031:analogs & derivatives*; D011817:Rabbits; D013056:Spectrophotometry, Ultraviolet; D013774:Tetranitromethane / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D014443:Tyrosine; D003577:Cytochrome P-450 Enzyme System; D013774:Tetranitromethane; D008697:Methane