Structural heterogeneity and conformational relaxation in heme proteins
The influence of cooling rate upon the structural heterogeneity of sperm whale myoglobin solutions at cryogenic temperatures was studied. Sample cooling rates were varied by almost four orders of magnitude. FTIR spectra of the CO stretch frequency region reveal that the population of the A states is...
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ftunivillidea:oai:www.ideals.illinois.edu:2142/21974 2023-05-15T18:26:40+02:00 Structural heterogeneity and conformational relaxation in heme proteins Chu, Kelvin Nienhaus, Uli 1995 http://hdl.handle.net/2142/21974 eng eng http://hdl.handle.net/2142/21974 (UMI)AAI9624317 AAI9624317 Copyright 1995 Chu, Kelvin Chemistry Physical Physics Molecular Biophysics General text 1995 ftunivillidea 2014-01-12T19:38:12Z The influence of cooling rate upon the structural heterogeneity of sperm whale myoglobin solutions at cryogenic temperatures was studied. Sample cooling rates were varied by almost four orders of magnitude. FTIR spectra of the CO stretch frequency region reveal that the population of the A states is highly sensitive to the glass transition temperature T$\sb{\rm g}$ of the solvent, which is in turn sensitive to the cooling rate. The structural heterogeneity within each substate was assessed by temperature-derivative spectroscopy (TDS); no significant changes of barrier distributions were found. We conclude that cooling rate plays a negligible role in the structural heterogeneity of protein solutions, and that conformational substates are an intrinsic part of protein systems. Flash photolysis experiments using both O$\sb2$ and CO adducts of sperm whale and horse myoglobin reveal an intermediate process that separates geminate and solvent rebinding. This process, named process II, is caused by thermally-induced relaxation (TIR) of the protein from the photoproduct (Mb*) to the deoxy (Mb) configuration. The conformational change Mb* $\rightarrow$ Mb was originally modelled as a smooth shift of the rebinding barrier distribution towards higher enthalpies by extrapolation of the spectral position of band III and rebinding enthalpy. Data from light-induced relaxation (LIR) experiments suggest that the relaxation proceeds in discrete steps. A four-well sequential model is proposed in which a conformational change separates the inner two wells. Text Sperm whale University of Illinois at Urbana-Champaign: IDEALS (Illinois Digital Environment for Access to Learning and Scholarship) |
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University of Illinois at Urbana-Champaign: IDEALS (Illinois Digital Environment for Access to Learning and Scholarship) |
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ftunivillidea |
language |
English |
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Chemistry Physical Physics Molecular Biophysics General |
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Chemistry Physical Physics Molecular Biophysics General Chu, Kelvin Structural heterogeneity and conformational relaxation in heme proteins |
topic_facet |
Chemistry Physical Physics Molecular Biophysics General |
description |
The influence of cooling rate upon the structural heterogeneity of sperm whale myoglobin solutions at cryogenic temperatures was studied. Sample cooling rates were varied by almost four orders of magnitude. FTIR spectra of the CO stretch frequency region reveal that the population of the A states is highly sensitive to the glass transition temperature T$\sb{\rm g}$ of the solvent, which is in turn sensitive to the cooling rate. The structural heterogeneity within each substate was assessed by temperature-derivative spectroscopy (TDS); no significant changes of barrier distributions were found. We conclude that cooling rate plays a negligible role in the structural heterogeneity of protein solutions, and that conformational substates are an intrinsic part of protein systems. Flash photolysis experiments using both O$\sb2$ and CO adducts of sperm whale and horse myoglobin reveal an intermediate process that separates geminate and solvent rebinding. This process, named process II, is caused by thermally-induced relaxation (TIR) of the protein from the photoproduct (Mb*) to the deoxy (Mb) configuration. The conformational change Mb* $\rightarrow$ Mb was originally modelled as a smooth shift of the rebinding barrier distribution towards higher enthalpies by extrapolation of the spectral position of band III and rebinding enthalpy. Data from light-induced relaxation (LIR) experiments suggest that the relaxation proceeds in discrete steps. A four-well sequential model is proposed in which a conformational change separates the inner two wells. |
author2 |
Nienhaus, Uli |
format |
Text |
author |
Chu, Kelvin |
author_facet |
Chu, Kelvin |
author_sort |
Chu, Kelvin |
title |
Structural heterogeneity and conformational relaxation in heme proteins |
title_short |
Structural heterogeneity and conformational relaxation in heme proteins |
title_full |
Structural heterogeneity and conformational relaxation in heme proteins |
title_fullStr |
Structural heterogeneity and conformational relaxation in heme proteins |
title_full_unstemmed |
Structural heterogeneity and conformational relaxation in heme proteins |
title_sort |
structural heterogeneity and conformational relaxation in heme proteins |
publishDate |
1995 |
url |
http://hdl.handle.net/2142/21974 |
genre |
Sperm whale |
genre_facet |
Sperm whale |
op_relation |
http://hdl.handle.net/2142/21974 (UMI)AAI9624317 AAI9624317 |
op_rights |
Copyright 1995 Chu, Kelvin |
_version_ |
1766208638576230400 |