Ligand binding to heme proteins: III. FTIR studies of His-E7 and Val-E11 mutants of carbonmonoxymyoglobin.
Fouier-transform infrared (FTIR) difference spectra of several His-E7 and Val-E11 mutants of sperm whale carbonmonoxymyoglobin were obtained by photodissociation at cryogenic temperatures. The IR absorption of the CO ligand shows characteristic features for each of the mutants, both in the ligand-bo...
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1993
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ftpubmed:oai:pubmedcentral.nih.gov:1225985 2023-05-15T18:26:53+02:00 Ligand binding to heme proteins: III. FTIR studies of His-E7 and Val-E11 mutants of carbonmonoxymyoglobin. Braunstein, D. P. Chu, K. Egeberg, K. D. Frauenfelder, H. Mourant, J. R. Nienhaus, G. U. Ormos, P. Sligar, S. G. Springer, B. A. Young, R. D. 1993-12 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1225985 http://www.ncbi.nlm.nih.gov/pubmed/8312483 https://doi.org/10.1016/S0006-3495(93)81310-9 en eng The Biophysical Society http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1225985 http://www.ncbi.nlm.nih.gov/pubmed/8312483 http://dx.doi.org/10.1016/S0006-3495(93)81310-9 Research Article Text 1993 ftpubmed https://doi.org/10.1016/S0006-3495(93)81310-9 2013-08-30T14:19:54Z Fouier-transform infrared (FTIR) difference spectra of several His-E7 and Val-E11 mutants of sperm whale carbonmonoxymyoglobin were obtained by photodissociation at cryogenic temperatures. The IR absorption of the CO ligand shows characteristic features for each of the mutants, both in the ligand-bound (A) state and in the photodissociated (B) state. For most of the mutants, a single A substate band is observed, which points to the crucial role of the His-E7 residue in determining the A substrate spectrum of the bound CO in the native structure. The fact that some of the mutants show more than one stretch band of the bound CO indicates that the appearance of multiple A substates is not exclusively connected to the presence of His-E7. In all but one mutant, multiple stretch bands of the CO in the photodissociated state are observed; these B substates are thought to arise from discrete positions and/or orientations of the photodissociated ligand in the heme pocket. The red shifts of the B bands with respect to the free-gas frequency indicate weak binding in the heme pocket. The observation of similar red shifts in microperoxidase (MP-8), where there is no residue on the distal side, suggests that the photodissociated ligand is still associated with the heme iron. Photoselection experiments were performed to determine the orientation of the bound ligand with respect to the heme normal by photolyzing small fractions of the sample with linearly polarized light at 540 nm. The resulting linear dichroism in the CO stretch spectrum yielded angles alpha > 20 degrees between the CO molecular axis and the heme normal for all of the mutants. We conclude that the off-axis position of the CO ligand in the native structure does not arise from steric constraints imposed by the distal histidine. There is no clear correlation between the size of the distal residue and the alpha of the CO ligand. Text Sperm whale PubMed Central (PMC) Biophysical Journal 65 6 2447 2454 |
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Research Article Braunstein, D. P. Chu, K. Egeberg, K. D. Frauenfelder, H. Mourant, J. R. Nienhaus, G. U. Ormos, P. Sligar, S. G. Springer, B. A. Young, R. D. Ligand binding to heme proteins: III. FTIR studies of His-E7 and Val-E11 mutants of carbonmonoxymyoglobin. |
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Research Article |
description |
Fouier-transform infrared (FTIR) difference spectra of several His-E7 and Val-E11 mutants of sperm whale carbonmonoxymyoglobin were obtained by photodissociation at cryogenic temperatures. The IR absorption of the CO ligand shows characteristic features for each of the mutants, both in the ligand-bound (A) state and in the photodissociated (B) state. For most of the mutants, a single A substate band is observed, which points to the crucial role of the His-E7 residue in determining the A substrate spectrum of the bound CO in the native structure. The fact that some of the mutants show more than one stretch band of the bound CO indicates that the appearance of multiple A substates is not exclusively connected to the presence of His-E7. In all but one mutant, multiple stretch bands of the CO in the photodissociated state are observed; these B substates are thought to arise from discrete positions and/or orientations of the photodissociated ligand in the heme pocket. The red shifts of the B bands with respect to the free-gas frequency indicate weak binding in the heme pocket. The observation of similar red shifts in microperoxidase (MP-8), where there is no residue on the distal side, suggests that the photodissociated ligand is still associated with the heme iron. Photoselection experiments were performed to determine the orientation of the bound ligand with respect to the heme normal by photolyzing small fractions of the sample with linearly polarized light at 540 nm. The resulting linear dichroism in the CO stretch spectrum yielded angles alpha > 20 degrees between the CO molecular axis and the heme normal for all of the mutants. We conclude that the off-axis position of the CO ligand in the native structure does not arise from steric constraints imposed by the distal histidine. There is no clear correlation between the size of the distal residue and the alpha of the CO ligand. |
format |
Text |
author |
Braunstein, D. P. Chu, K. Egeberg, K. D. Frauenfelder, H. Mourant, J. R. Nienhaus, G. U. Ormos, P. Sligar, S. G. Springer, B. A. Young, R. D. |
author_facet |
Braunstein, D. P. Chu, K. Egeberg, K. D. Frauenfelder, H. Mourant, J. R. Nienhaus, G. U. Ormos, P. Sligar, S. G. Springer, B. A. Young, R. D. |
author_sort |
Braunstein, D. P. |
title |
Ligand binding to heme proteins: III. FTIR studies of His-E7 and Val-E11 mutants of carbonmonoxymyoglobin. |
title_short |
Ligand binding to heme proteins: III. FTIR studies of His-E7 and Val-E11 mutants of carbonmonoxymyoglobin. |
title_full |
Ligand binding to heme proteins: III. FTIR studies of His-E7 and Val-E11 mutants of carbonmonoxymyoglobin. |
title_fullStr |
Ligand binding to heme proteins: III. FTIR studies of His-E7 and Val-E11 mutants of carbonmonoxymyoglobin. |
title_full_unstemmed |
Ligand binding to heme proteins: III. FTIR studies of His-E7 and Val-E11 mutants of carbonmonoxymyoglobin. |
title_sort |
ligand binding to heme proteins: iii. ftir studies of his-e7 and val-e11 mutants of carbonmonoxymyoglobin. |
publisher |
The Biophysical Society |
publishDate |
1993 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1225985 http://www.ncbi.nlm.nih.gov/pubmed/8312483 https://doi.org/10.1016/S0006-3495(93)81310-9 |
genre |
Sperm whale |
genre_facet |
Sperm whale |
op_relation |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1225985 http://www.ncbi.nlm.nih.gov/pubmed/8312483 http://dx.doi.org/10.1016/S0006-3495(93)81310-9 |
op_doi |
https://doi.org/10.1016/S0006-3495(93)81310-9 |
container_title |
Biophysical Journal |
container_volume |
65 |
container_issue |
6 |
container_start_page |
2447 |
op_container_end_page |
2454 |
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1766208848473882624 |