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

*此作品的通信作者

研究成果: 雜誌貢獻期刊論文同行評審

64 引文 斯高帕斯(Scopus)

摘要

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.

原文英語
頁(從 - 到)1485-1489
頁數5
期刊Journal of the American Chemical Society
115
發行號4
DOIs
出版狀態已發佈 - 1993 二月 1

ASJC Scopus subject areas

  • 催化
  • 化學 (全部)
  • 生物化學
  • 膠體和表面化學

指紋

深入研究「Electron Transfer in Ruthenium/Zinc Porphyrin Derivatives of Recombinant Human Myoglobins. Analysis of Tunneling Pathways in Myoglobin and Cytochrome c」主題。共同形成了獨特的指紋。

引用此