| Inhomogeneous broadening in spectral bands of carbonmonoxymyoglobin. The connection between spectral and functional heterogeneity. | |
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MedLine Citation:
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PMID: 2317545 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The rebinding kinetics of CO to myoglobin after flash photolysis is nonexponential in time below approximately 180 K; the kinetics is governed by a distribution of enthalpic barriers. This distribution results from inhomogeneities in the protein conformation, referred to as conformational substates. Hole-burning experiments on the Soret and IR CO-stretch bands test the assumption that an inhomogeneous distribution of conformational substates results in inhomogeneously broadened spectra. CO was slowly photolyzed at different wavelengths in the Soret band at 10 K. Both the Soret band and the CO-stretch band A1, centered at 1,945 cm-1, shift during photolysis, demonstrating that different wavelengths excite different parts of the distributed population. We have also done kinetic hole-burning experiments by measuring peak shifts in the Soret and A1 bands as the CO molecules rebind. The shifts indicate that the spectral and enthalpic distributions are correlated. In the A1 band, the spectral and enthalpic distributions are highly correlated while in the Soret the correlation is weak. From the peak shifts in the spectral and kinetic hole-burning experiments the inhomogeneous broadening is estimated to be approximately 15% of the total width in the Soret band and approximately 60% in A1. We have previously measured the tilt angle alpha between the bound CO and the heme normal (Ormos, P., D. Braunstein, H. Frauenfelder, M. K. Hong, S.-L. Lin, T. B. Sauke, and R. D. Young. 1988. Proc. Natl. Acad. Sci. USA. 85:8492-8496) and observed a wave number dependence of the tilt angles within the CO-stretch A bands. Thus the spectral and enthalpic distributions of the A bands are coupled to a heterogeneity of the structure. |
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Authors:
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P Ormos; A Ansari; D Braunstein; B R Cowen; H Frauenfelder; M K Hong; I E Iben; T B Sauke; P J Steinbach; R D Young |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Biophysical journal Volume: 57 ISSN: 0006-3495 ISO Abbreviation: Biophys. J. Publication Date: 1990 Feb |
Date Detail:
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Created Date: 1990-05-07 Completed Date: 1990-05-07 Revised Date: 2010-09-09 |
Medline Journal Info:
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Nlm Unique ID: 0370626 Medline TA: Biophys J Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 191-9 Citation Subset: IM |
Affiliation:
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Department of Physics, University of Illinois, Urbana 61801. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Binding Sites Carbon Monoxide / metabolism Kinetics Myoglobin / metabolism* Protein Binding Protein Conformation Spectrophotometry / methods |
| Grant Support | |
ID/Acronym/Agency:
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GM 18051/GM/NIGMS NIH HHS; GM 32455/GM/NIGMS NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Myoglobin; 0/carboxymyoglobin; 630-08-0/Carbon Monoxide |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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