Electron Transfer in Ruthenium/Zinc Porphyrin Derivatives of Recombinant Human Myoglobins. Analysis of Tunneling Pathways in Myoglobin and Cytochrome c

Danilo R. Casimiro, Luet L. Wong, Jorge L. Colón, Thomas E. Zewert, John H. Richards, I. Jy Chang, Jay R. Winkler, Harry B. Gray

Research output: Contribution to journalArticle

64 Citations (Scopus)

Abstract

Site-directed mutants of human myoglobin have been prepared and characterized; each protein has a single surface-modifiable histidine (at position 48, 70, or 83). The proteins were modified by covalent attachment of pentaammineruthenium (a5Ru) to the surface histidine and substitution of zinc mesoporphyrin IX diacid (ZnP) for the heme. Donor-acceptor separations (edge-edge distances d) in the modified proteins are 9.5 Å, His70; 12.7 Å, His48; and 15.5 Å, His83. Rates of photoinduced electron transfer in these ruthenium-modified myoglobins were measured by transient absorption spectroscopy. The 3ZnP*→ Ru3+ rate constants are 1.6 × 107 (His70), 7.2 × 104 (His48), and 4.0 × 102 s−1 (His83) (−ΔG° = 0.82 eV); charge-recombination (Ru2+→ZnP+) rates are 1.1 × 105 (His48) and 7.3 × 102 s−1 (His83) (−ΔG° = 0.96 eV). Activationless (maximum) rates assuming λ = 1.3 eV are 7.2 × 107 (His70), 3.3 × 105 (His48), and 1.8 × 103 s−1 (His83). Distant electronic couplings, which limit the maximum rates in the modified myoglobins, have been analyzed along with data from Ru-modified cytochromes c in terms of a tunneling pathway model. Single dominant pathways adequately describe the electronic couplings in cytochrome c but do not satisfactorily account for the myoglobin couplings. The correlation of electronic coupling with tunneling length for myoglobin is improved significantly by the inclusion of multiple pathways.

Original languageEnglish
Pages (from-to)1485-1489
Number of pages5
JournalJournal of the American Chemical Society
Volume115
Issue number4
DOIs
Publication statusPublished - 1993 Feb 1

Fingerprint

Ruthenium
Myoglobin
Porphyrins
Cytochromes c
Zinc
Electrons
Derivatives
Proteins
Histidine
Heme
Absorption spectroscopy
Genetic Recombination
Rate constants
Spectrum Analysis
Substitution reactions
zinc hematoporphyrin

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Electron Transfer in Ruthenium/Zinc Porphyrin Derivatives of Recombinant Human Myoglobins. Analysis of Tunneling Pathways in Myoglobin and Cytochrome c. / Casimiro, Danilo R.; Wong, Luet L.; Colón, Jorge L.; Zewert, Thomas E.; Richards, John H.; Chang, I. Jy; Winkler, Jay R.; Gray, Harry B.

In: Journal of the American Chemical Society, Vol. 115, No. 4, 01.02.1993, p. 1485-1489.

Research output: Contribution to journalArticle

Casimiro, Danilo R. ; Wong, Luet L. ; Colón, Jorge L. ; Zewert, Thomas E. ; Richards, John H. ; Chang, I. Jy ; Winkler, Jay R. ; Gray, Harry B. / Electron Transfer in Ruthenium/Zinc Porphyrin Derivatives of Recombinant Human Myoglobins. Analysis of Tunneling Pathways in Myoglobin and Cytochrome c. In: Journal of the American Chemical Society. 1993 ; Vol. 115, No. 4. pp. 1485-1489.
@article{24c15fd4dbfe4b188764dd133bf74fd7,
title = "Electron Transfer in Ruthenium/Zinc Porphyrin Derivatives of Recombinant Human Myoglobins. Analysis of Tunneling Pathways in Myoglobin and Cytochrome c",
abstract = "Site-directed mutants of human myoglobin have been prepared and characterized; each protein has a single surface-modifiable histidine (at position 48, 70, or 83). The proteins were modified by covalent attachment of pentaammineruthenium (a5Ru) to the surface histidine and substitution of zinc mesoporphyrin IX diacid (ZnP) for the heme. Donor-acceptor separations (edge-edge distances d) in the modified proteins are 9.5 {\AA}, His70; 12.7 {\AA}, His48; and 15.5 {\AA}, His83. Rates of photoinduced electron transfer in these ruthenium-modified myoglobins were measured by transient absorption spectroscopy. The 3ZnP*→ Ru3+ rate constants are 1.6 × 107 (His70), 7.2 × 104 (His48), and 4.0 × 102 s−1 (His83) (−ΔG° = 0.82 eV); charge-recombination (Ru2+→ZnP+) rates are 1.1 × 105 (His48) and 7.3 × 102 s−1 (His83) (−ΔG° = 0.96 eV). Activationless (maximum) rates assuming λ = 1.3 eV are 7.2 × 107 (His70), 3.3 × 105 (His48), and 1.8 × 103 s−1 (His83). Distant electronic couplings, which limit the maximum rates in the modified myoglobins, have been analyzed along with data from Ru-modified cytochromes c in terms of a tunneling pathway model. Single dominant pathways adequately describe the electronic couplings in cytochrome c but do not satisfactorily account for the myoglobin couplings. The correlation of electronic coupling with tunneling length for myoglobin is improved significantly by the inclusion of multiple pathways.",
author = "Casimiro, {Danilo R.} and Wong, {Luet L.} and Col{\'o}n, {Jorge L.} and Zewert, {Thomas E.} and Richards, {John H.} and Chang, {I. Jy} and Winkler, {Jay R.} and Gray, {Harry B.}",
year = "1993",
month = "2",
day = "1",
doi = "10.1021/ja00057a037",
language = "English",
volume = "115",
pages = "1485--1489",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "4",

}

TY - JOUR

T1 - Electron Transfer in Ruthenium/Zinc Porphyrin Derivatives of Recombinant Human Myoglobins. Analysis of Tunneling Pathways in Myoglobin and Cytochrome c

AU - Casimiro, Danilo R.

AU - Wong, Luet L.

AU - Colón, Jorge L.

AU - Zewert, Thomas E.

AU - Richards, John H.

AU - Chang, I. Jy

AU - Winkler, Jay R.

AU - Gray, Harry B.

PY - 1993/2/1

Y1 - 1993/2/1

N2 - Site-directed mutants of human myoglobin have been prepared and characterized; each protein has a single surface-modifiable histidine (at position 48, 70, or 83). The proteins were modified by covalent attachment of pentaammineruthenium (a5Ru) to the surface histidine and substitution of zinc mesoporphyrin IX diacid (ZnP) for the heme. Donor-acceptor separations (edge-edge distances d) in the modified proteins are 9.5 Å, His70; 12.7 Å, His48; and 15.5 Å, His83. Rates of photoinduced electron transfer in these ruthenium-modified myoglobins were measured by transient absorption spectroscopy. The 3ZnP*→ Ru3+ rate constants are 1.6 × 107 (His70), 7.2 × 104 (His48), and 4.0 × 102 s−1 (His83) (−ΔG° = 0.82 eV); charge-recombination (Ru2+→ZnP+) rates are 1.1 × 105 (His48) and 7.3 × 102 s−1 (His83) (−ΔG° = 0.96 eV). Activationless (maximum) rates assuming λ = 1.3 eV are 7.2 × 107 (His70), 3.3 × 105 (His48), and 1.8 × 103 s−1 (His83). Distant electronic couplings, which limit the maximum rates in the modified myoglobins, have been analyzed along with data from Ru-modified cytochromes c in terms of a tunneling pathway model. Single dominant pathways adequately describe the electronic couplings in cytochrome c but do not satisfactorily account for the myoglobin couplings. The correlation of electronic coupling with tunneling length for myoglobin is improved significantly by the inclusion of multiple pathways.

AB - Site-directed mutants of human myoglobin have been prepared and characterized; each protein has a single surface-modifiable histidine (at position 48, 70, or 83). The proteins were modified by covalent attachment of pentaammineruthenium (a5Ru) to the surface histidine and substitution of zinc mesoporphyrin IX diacid (ZnP) for the heme. Donor-acceptor separations (edge-edge distances d) in the modified proteins are 9.5 Å, His70; 12.7 Å, His48; and 15.5 Å, His83. Rates of photoinduced electron transfer in these ruthenium-modified myoglobins were measured by transient absorption spectroscopy. The 3ZnP*→ Ru3+ rate constants are 1.6 × 107 (His70), 7.2 × 104 (His48), and 4.0 × 102 s−1 (His83) (−ΔG° = 0.82 eV); charge-recombination (Ru2+→ZnP+) rates are 1.1 × 105 (His48) and 7.3 × 102 s−1 (His83) (−ΔG° = 0.96 eV). Activationless (maximum) rates assuming λ = 1.3 eV are 7.2 × 107 (His70), 3.3 × 105 (His48), and 1.8 × 103 s−1 (His83). Distant electronic couplings, which limit the maximum rates in the modified myoglobins, have been analyzed along with data from Ru-modified cytochromes c in terms of a tunneling pathway model. Single dominant pathways adequately describe the electronic couplings in cytochrome c but do not satisfactorily account for the myoglobin couplings. The correlation of electronic coupling with tunneling length for myoglobin is improved significantly by the inclusion of multiple pathways.

UR - http://www.scopus.com/inward/record.url?scp=0001646455&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0001646455&partnerID=8YFLogxK

U2 - 10.1021/ja00057a037

DO - 10.1021/ja00057a037

M3 - Article

AN - SCOPUS:0001646455

VL - 115

SP - 1485

EP - 1489

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 4

ER -