These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Endogenous cysteine ligation in ferric and ferrous cytochrome P-450. Direct evidence from x-ray absorption spectroscopy.
    Author: Hahn JE, Hodgson KO, Andersson LA, Dawson JH.
    Journal: J Biol Chem; 1982 Sep 25; 257(18):10934-41. PubMed ID: 7107639.
    Abstract:
    Extended x-ray absorption fine structure spectroscopy has been applied to the elucidation of the structure of the heme iron site of bacterial cytochrome P-450. The low spin ferric, high spin ferric, ferrous, and ferrous carbonyl states of the enzyme have been examined. Curve-fitting analysis of the data provides direct and compelling evidence for the presence of a sulfur atom in the first coordination sphere of the iron. The iron-nitrogen (porphyrin) distances indicate five coordination in high spin ferric and ferrous P-450 and six coordination in low spin ferric and ferrous carbonyl P-450. The iron-sulfur distances are consistent with thiolate ligation, presumably from cysteinate, in all four states of the enzyme. In each case, the iron-sulfur bond distance is equal to or shorter than the analogous Fe-S bonds in model iron porphyrin thiolate complexes whose crystal structures have been determined. Since known thiol-sulfur:iron-heme bond distances are noticeably longer than the corresponding thiolate bonds, the X-ray absorption fine structure results strongly suggest that, in each P-450 state examined, the sulfur donor is a thiolate. The results reported in this paper concerning the ligand identity, state of protonation, and metal-ligand bond distances are of critical importance to a complete description of the P-450 reaction cycle and its mechanism of oxygen activation.
    [Abstract] [Full Text] [Related] [New Search]