title: Inactivation of myoglobin by ortho-substituted arylhydrazines. Formation of prosthetic heme aryl-iron but not N-aryl adducts.
abstract: Stable phenyl-iron complexes are known to form in the reactions of myoglobin, hemoglobin, and catalase with phenylhydrazine. The phenyl moiety in these complexes migrates from the iron to a nitrogen of the porphyrin upon denaturation of the hemoproteins. Complexes obtained from myoglobin and ortho-substituted phenylhydrazines, however, are much less stable, have distinct chromophores, and do not yield N-arylporphyrins. These abnormal properties imply that the complexes differ in structure (e.g., they are aryldiazenyl-rather than aryl-iron complexes) or that ortho substitution strongly alters the chemistry of aryl-iron complexes. The present NMR studies unambiguously demonstrate that ortho-substituted phenylhydrazines give normal aryl-iron complexes but that the aryl group in these complexes is conformationally locked and is unable to shift from iron to nitrogen.
mesh_terms: D000818:Animals; D003903:Deuterium; D006418:Heme / Q000378:metabolism; D006834:Hydrazines / Q000138:chemical synthesis* / Q000494:pharmacology; D007501:Iron / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008786:Metmyoglobin / Q000378:metabolism; D008958:Models, Molecular; D009211:Myoglobin / Q000037:antagonists & inhibitors*; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D014907:Whales; D014961:X-Ray Diffraction
chemical_list: D006834:Hydrazines; D009211:Myoglobin; D008786:Metmyoglobin; D006418:Heme; D003903:Deuterium; D007501:Iron