Document Detail


Photoinduced carbon monoxide migration in a synthetic heme-copper complex.
MedLine Citation:
PMID:  15853327     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Time-resolved infrared (TRIR) flash photolytic techniques have been employed to initiate and observe the efficient dissociation of CO from a synthetic heme-CO/copper complex, [((6)L)Fe(II)(CO)..Cu(I)](+) (2), in CH(3)CN and acetone at room temperature. In CH(3)CN, a significant fraction of the photodissociated CO molecules transiently bind to copper (nu(CO)(Cu) = 2091 cm(-)(1)) giving [((6)L)Fe(II)..Cu(I)(CO)](+) (4), with an observed rate constant, k(1) = 1.5 x 10(5) s(-)(1). That is followed by a slower direct transfer of CO from the copper moiety back to the heme (nu(CO)(Fe) = 1975 cm(-)(1)) with k(2) = 1600 s(-)(1). Additional transient absorption (TA) UV-vis spectroscopic experiments have been performed monitoring the CO-transfer reaction by following the Soret band. Eyring analysis of the temperature-dependent data yields DeltaH(double dagger) = 43.9 kJ mol(-)(1) for the 4-to-2 transformation, similar to that for CO dissociation from [Cu(I)(tmpa)(CO)](+) in CH(3)CN (DeltaH(double dagger) = 43.6 kJ mol(-)(1)), suggesting CO dissociation from copper regulates the binding of small molecules to the heme within [((6)L)Fe(II)..Cu(I)](+)(3). Our observations are analagous to those observed for the heme(a3)/Cu(B) active site of cytochrome c oxidase, where photodissociated CO from the heme(a3) site immediately (ps) transfers to Cu(B) followed by millisecond transfer back to the heme.
Authors:
H Christopher Fry; Andrew D Cohen; John P Toscano; Gerald J Meyer; Kenneth D Karlin
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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.    
Journal Detail:
Title:  Journal of the American Chemical Society     Volume:  127     ISSN:  0002-7863     ISO Abbreviation:  J. Am. Chem. Soc.     Publication Date:  2005 May 
Date Detail:
Created Date:  2005-04-27     Completed Date:  2005-06-23     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7503056     Medline TA:  J Am Chem Soc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  6225-30     Citation Subset:  IM    
Affiliation:
Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
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MeSH Terms
Descriptor/Qualifier:
Carbon Monoxide / chemistry*,  radiation effects
Copper / chemistry*
Heme / chemistry*,  radiation effects
Iron Compounds / chemistry
Kinetics
Models, Molecular
Photolysis
Spectrophotometry, Infrared / methods
Spectrophotometry, Ultraviolet
Chemical
Reg. No./Substance:
0/Iron Compounds; 14875-96-8/Heme; 630-08-0/Carbon Monoxide; 7440-50-8/Copper

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


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