Document Detail

Circular dichroism studies of low-spin ferric cytochrome P-450CAM ligand complexes.
MedLine Citation:
PMID:  6639949     Owner:  NLM     Status:  MEDLINE    
Circular dichroism (CD) spectroscopy has been used to probe the active site of bacterial ferric cytochrome P-450CAM. The endogenous sixth ligand to the heme iron has been displaced by an extensive series of exogenous oxygen, nitrogen, sulfur and other neutral and anionic donor ligands in an attempt to examine systematically the steric and electronic factors that influence the coupling of the heme chromophore to its protein environment. General trends for each ligand class are reported and discussed. Both the wavelengths and the intensities of the CD bands vary with ligand type and structure. All but one of the complexes exhibit negative CD maxima in their delta and Soret bands. Comparison to ferric myoglobin-thiolate complexes indicates that the negative sign observed for the cytochrome P-450 spectra is not a property of the thiolate fifth ligand, but rather arises from a different interaction of the cytochrome P-450 heme with its protein environment. Complexes with neutral oxygen donors display CD spectra that most closely resemble the spectrum of the native low-spin enzyme. Hyperporphyrin (split Soret) cytochrome P-450 complexes with thiolates, phosphines and cyanide trans to cysteinate have complex CD spectra, reflecting the intrinsic non-degeneracy of the Soret pi pi transitions. The extensive work presented herein provides an empirical foundation for use in analyzing the interaction of heme chromophores with their protein surroundings, not only for the cytochrome P-450 monooxygenases but also for heme proteins in general.
L A Andersson; M Sono; J H Dawson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  748     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  1983 Nov 
Date Detail:
Created Date:  1984-01-26     Completed Date:  1984-01-26     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  341-52     Citation Subset:  IM    
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MeSH Terms
Circular Dichroism
Cytochrome P-450 Enzyme System / metabolism*
Nitrogen / metabolism
Oxygen / metabolism
Pseudomonas / enzymology
Sulfur / metabolism
Grant Support
Reg. No./Substance:
7704-34-9/Sulfur; 7727-37-9/Nitrogen; 7782-44-7/Oxygen; 9035-51-2/Cytochrome P-450 Enzyme System

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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