Distance dependence of photoinduced long-range electron transfer in zinc/ruthenium-modified myoglobins
An experimental investigation of the distance dependence of long-range electron transfer in zinc/ruthenium-modified myoglobins has been performed. The modified proteins were prepared by substitution of zinc mesoporphyrin IX diacid (ZnP) for the heme in each of four previously characterized pentaammi...
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American Chemical Society
1988
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Online Access: | https://doi.org/10.1021/ja00210a020 |
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ftcaltechauth:oai:authors.library.caltech.edu:nbks5-30s45 2024-06-23T07:56:59+00:00 Distance dependence of photoinduced long-range electron transfer in zinc/ruthenium-modified myoglobins Axup, Andrew W. Albin, Michael Mayo, Stephen L. Crutchley, Robert J. Gray, Harry B. 1988-01-20 https://doi.org/10.1021/ja00210a020 unknown American Chemical Society https://doi.org/10.1021/ja00210a020 oai:authors.library.caltech.edu:nbks5-30s45 eprintid:24137 resolverid:CaltechAUTHORS:20110620-160435945 info:eu-repo/semantics/openAccess Other Journal of the American Chemical Society, 110(2), 435-439, (1988-01-20) info:eu-repo/semantics/article 1988 ftcaltechauth https://doi.org/10.1021/ja00210a020 2024-06-12T02:34:56Z An experimental investigation of the distance dependence of long-range electron transfer in zinc/ruthenium-modified myoglobins has been performed. The modified proteins were prepared by substitution of zinc mesoporphyrin IX diacid (ZnP) for the heme in each of four previously characterized pentaammineruthenium(III) (a_5Ru;a = NH_3) derivatives of sperm whale myoglobin (Mb): a_5Ru(His-48)Mb, a_5Ru(His-12)Mb, a_5Ru(His-116)Mb, a_5Ru(His-81)Mb. Electron transfer from the ZnP triplet excited state (^3ZnP*) to Ru^3+, ^3ZnP*-Ru^3+ → ZnP^+-Ru^2+ (ΔE° ~ 0.8V) was measured by time-resolved transient absorption spectroscopy: rate constants (k_f) are 7.0 × 10^4 (His-48), 1.0 × 10^2 (His-12), 8.9 × 10^1 (His-116), and 8.5 × 10^1 (His-81) s^-1 at 25 °C. Activation enthalpies calculated from the temperature dependences of the electron-transfer rates over the range 5-40 °C are 1.7 ± 1.6 (His-48), 4.7 ± 0.9 (His-12), 5.4 ± 0.4 (His-116), and 5.6 ± 2.5 (His-81) kcal mol^-1. Electron-transfer distances (d = closest ZnP edge to a_5Ru(His) edge; angstroms) were calculated to fall in the following ranges: His-48, 11.8-16.6; His-12, 21.5-22.3; His-116, 19.8-20.4; His-81, 18.8-19.3. The rate-distance equation is k_f = 7.8 × 10^8 exp[-0.9l(d - 3)] s^-1 . The data indicate that the ^3ZnP*-Ru(His-12)^3+ electronic coupling may be enhanced by an intervening tryptophan (Trp-14). © 1988 American Chemical Society. Received May 8, 1987. Publication Date: January 1988. Contribution No. 7588 from the Arthur Amos Noyes Laboratory, California Institute of Technology, Pasadena, California 91125. We thank Charlie Lieber, Jenny Karas, Walther Ellis, Lome Reid, Jose Onuchic, David Beratan, A. Kuki, Harvey Schugar, R. A. Marcus, and Jay Winkler for helpful discussions. A.W.A. acknowledges a fellowship from the Fannie and John Hertz Foundation. S.L.M. acknowledges a fellowship from AT&T Bell Laboratories. This research was supported by National Science Foundation Grants CHE85-18793 and CHE85-09637. Published - ... Article in Journal/Newspaper Sperm whale Caltech Authors (California Institute of Technology) Jenny ENVELOPE(-68.417,-68.417,-67.733,-67.733) Journal of the American Chemical Society 110 2 435 439 |
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Caltech Authors (California Institute of Technology) |
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An experimental investigation of the distance dependence of long-range electron transfer in zinc/ruthenium-modified myoglobins has been performed. The modified proteins were prepared by substitution of zinc mesoporphyrin IX diacid (ZnP) for the heme in each of four previously characterized pentaammineruthenium(III) (a_5Ru;a = NH_3) derivatives of sperm whale myoglobin (Mb): a_5Ru(His-48)Mb, a_5Ru(His-12)Mb, a_5Ru(His-116)Mb, a_5Ru(His-81)Mb. Electron transfer from the ZnP triplet excited state (^3ZnP*) to Ru^3+, ^3ZnP*-Ru^3+ → ZnP^+-Ru^2+ (ΔE° ~ 0.8V) was measured by time-resolved transient absorption spectroscopy: rate constants (k_f) are 7.0 × 10^4 (His-48), 1.0 × 10^2 (His-12), 8.9 × 10^1 (His-116), and 8.5 × 10^1 (His-81) s^-1 at 25 °C. Activation enthalpies calculated from the temperature dependences of the electron-transfer rates over the range 5-40 °C are 1.7 ± 1.6 (His-48), 4.7 ± 0.9 (His-12), 5.4 ± 0.4 (His-116), and 5.6 ± 2.5 (His-81) kcal mol^-1. Electron-transfer distances (d = closest ZnP edge to a_5Ru(His) edge; angstroms) were calculated to fall in the following ranges: His-48, 11.8-16.6; His-12, 21.5-22.3; His-116, 19.8-20.4; His-81, 18.8-19.3. The rate-distance equation is k_f = 7.8 × 10^8 exp[-0.9l(d - 3)] s^-1 . The data indicate that the ^3ZnP*-Ru(His-12)^3+ electronic coupling may be enhanced by an intervening tryptophan (Trp-14). © 1988 American Chemical Society. Received May 8, 1987. Publication Date: January 1988. Contribution No. 7588 from the Arthur Amos Noyes Laboratory, California Institute of Technology, Pasadena, California 91125. We thank Charlie Lieber, Jenny Karas, Walther Ellis, Lome Reid, Jose Onuchic, David Beratan, A. Kuki, Harvey Schugar, R. A. Marcus, and Jay Winkler for helpful discussions. A.W.A. acknowledges a fellowship from the Fannie and John Hertz Foundation. S.L.M. acknowledges a fellowship from AT&T Bell Laboratories. This research was supported by National Science Foundation Grants CHE85-18793 and CHE85-09637. Published - ... |
format |
Article in Journal/Newspaper |
author |
Axup, Andrew W. Albin, Michael Mayo, Stephen L. Crutchley, Robert J. Gray, Harry B. |
spellingShingle |
Axup, Andrew W. Albin, Michael Mayo, Stephen L. Crutchley, Robert J. Gray, Harry B. Distance dependence of photoinduced long-range electron transfer in zinc/ruthenium-modified myoglobins |
author_facet |
Axup, Andrew W. Albin, Michael Mayo, Stephen L. Crutchley, Robert J. Gray, Harry B. |
author_sort |
Axup, Andrew W. |
title |
Distance dependence of photoinduced long-range electron transfer in zinc/ruthenium-modified myoglobins |
title_short |
Distance dependence of photoinduced long-range electron transfer in zinc/ruthenium-modified myoglobins |
title_full |
Distance dependence of photoinduced long-range electron transfer in zinc/ruthenium-modified myoglobins |
title_fullStr |
Distance dependence of photoinduced long-range electron transfer in zinc/ruthenium-modified myoglobins |
title_full_unstemmed |
Distance dependence of photoinduced long-range electron transfer in zinc/ruthenium-modified myoglobins |
title_sort |
distance dependence of photoinduced long-range electron transfer in zinc/ruthenium-modified myoglobins |
publisher |
American Chemical Society |
publishDate |
1988 |
url |
https://doi.org/10.1021/ja00210a020 |
long_lat |
ENVELOPE(-68.417,-68.417,-67.733,-67.733) |
geographic |
Jenny |
geographic_facet |
Jenny |
genre |
Sperm whale |
genre_facet |
Sperm whale |
op_source |
Journal of the American Chemical Society, 110(2), 435-439, (1988-01-20) |
op_relation |
https://doi.org/10.1021/ja00210a020 oai:authors.library.caltech.edu:nbks5-30s45 eprintid:24137 resolverid:CaltechAUTHORS:20110620-160435945 |
op_rights |
info:eu-repo/semantics/openAccess Other |
op_doi |
https://doi.org/10.1021/ja00210a020 |
container_title |
Journal of the American Chemical Society |
container_volume |
110 |
container_issue |
2 |
container_start_page |
435 |
op_container_end_page |
439 |
_version_ |
1802650403947413504 |