Identification of the ligand trans to thiolate in cytochrome P-450 LM2 by chemical modification

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 tyrosina...

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Bibliographic Details
Published in:FEBS letters 1983-08, Vol.159 (1), p.58-62
Main Authors: Jänig, G.-R., Dettmer, R., Usanov, S.A., Ruckpaul, K.
Format: Article
Language:English
Subjects:
Active center
Animals
Chemical modification
Cytochrome P-450
Cytochrome P-450 Enzyme System - metabolism
flavoprotein-linked monooxygenase
iron
Isoenzymes - metabolism
Male
Methane - analogs & derivatives
phenobarbitone
Rabbits
Sixth ligand
Spectrophotometry, Ultraviolet
tetranitromethame
Tetranitromethane - metabolism
Tyrosine
Tyrosine - metabolism
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Summary: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.
ISSN:0014-5793
1873-3468
DOI:10.1016/0014-5793(83)80416-5