Ruthenium-modified Cytochrome Research Articles

The protein-folding speed limit: intrachain diffusion times set by electron-transfer rates in denatured Ru(NH3)5(His-33)-Zn-cytochrome c.

The kinetics of electron transfer from the triplet-excited Zn-porphyrin to a Ru(NH(3))(5)(His-33)(3+) complex have been measured in Zn-substituted ruthenium-modified cytochrome c under denaturing conditions. In the folded protein, the electron-tunneling rate constant is 7.5 x 10(5) s(-1). As the protein is denatured with guanidine hydrochloride, a faster adiabatic electron-transfer reaction appears (4.0 x 10(6) s(-1), [guanidine hydrochloride] = 5.4 M) that is limited by the rate of intrachain diffusion to bring the Zn-porphyrin and Ru complex into contact. The 250-ns contact time for formation of a 15-residue loop in denatured cytochrome c is in accord with a statistical model developed by Camacho and Thirumalai [Camacho, C. J. & Thirumalai, D. (1995) Proc. Natl. Acad. Sci. USA 92, 1277-1281] that predicts that the most probable transient loops formed in denatured proteins are comprised of 10 amino acids. Extrapolation of the cytochrome c contact time to a 10-residue loop sets the folding speed limit at approximately 10(7) s(-1).

Pressure Effects on the Rates of Intramolecular Electron Transfer in Ruthenium-Modified Cytochrome c. Role of the Intervening Medium in Tuning Distant Fe2+:Ru3+ Electronic Couplings

Pressure Effects on the Rates of Intramolecular Electron Transfer in Ruthenium-Modified Cytochrome c. Role of the Intervening Medium in Tuning Distant Fe2+:Ru3+ Electronic Couplings

Identification of Chemical Modification Sites on Metalloproteins by Capillary Electrophoresis

Capillary electrophoresis (CE) has been used to separate the peptides obtained from tryptic digestion of ruthenium-modified cytochrome c. The modified peptide was identified from a comparison of the elution profile and absorbance characteristics of the native and modified proteins. Automatic fraction collection on the CE instrument provides sufficient amounts of this modified peptide for amino acid sequencing. Capillary electrophoresis has also been used to monitor the modification reaction and to optimize the modification efficiency. The methodologies have been extended to myoglobin in order to monitor the modification of multiple surface sites.

Electron tunneling in ruthenium-modified cytochrome

Electron tunneling in ruthenium-modified cytochrome

Photoinduced electron transfer in ruthenium-modified cytochrome c

Abstract

Long-range electron transfer in ruthenium-modified cytochrome c: evaluation of porphyrin-ruthenium electronic couplings in the Candida krusei and horse heart proteins

Experiments in several laboratories have shown that electron transfer (ET) can take place at appreciable rates over long distances (> 10 {angstrom}) in organic and inorganic molecules and in proteins. There is a bewildering array of potential ET pathways in proteins; interestingly, the through-peptide routes (if there are any) generally involve so many bonds that they cannot possibly account for the observed rates. In searching for good pathways through cytochrome c, the authors discovered a relatively short route from His-39 to the heme in the Candida krusei (C.k.) protein. Along this route, the crucial shortcut is a hydrogen bond that bridges Gly-41 and the heme. Since experimental information relevant to protein pathway models is lacking, they have extracted donor-acceptor electronic coupling constants from an analysis of the driving-force dependence of ET rates in Ru(His-39)-modified C.k. zinc cytochrome c.

Electron transfer in heme and blue-copper proteins: ruthenium-modified cytochrome b 5 and azurin

Electron transfer in heme and blue-copper proteins: ruthenium-modified cytochrome b 5 and azurin

Driving-force effects on the rate of long-range electron transfer in ruthenium-modified cytochrome c

Two new Ru-modified, Zn-substituted derivatives of horse heart cytochrome c have been prepared, Rua{sub 4}L(histidine-33)-Zn-cyt c (a = NH{sub 3}; L = pyridine, isonicotinamide). Molecular mechanics modeling indicates that the 11.7 {angstrom} edge-to-edge separation between the redox centers is virtually identical with that reported for the Ru-pentaammine derivative. Rates of photoinduced charge separation and recombination in Rua{sub 4}L (His-33)-Zn-cyt c lie in the range of 2.0 {times} 10{sup 5}-3.3 {times} 10{sup 6} s{sup {minus}1} (22{degree}C). These kinetics, along with those already reported, provide a total of eight intramolecular electron-transfer reactions that have been measured in Ru-M-cyt c (M = Fe, Zn) at driving forces (-{Delta}G{degree}) ranging from 0.18 to 1.05 eV. The variation of the rate with driving force is in general agreement with the semiclassical theory of electron-transfer reactions. Fitting the Ru-Zn-cyt c charge-separation data yields a reorganization energy ({lambda}) of 1.15 (5) eV and an electronic coupling matrix element (H{sub AB}) of 0.13 (1) cm{sup {minus}1}. The charge-recombination data are fit with the parameters {lambda} = 1.24 (5) eV and H{sub AB} = 0.10 (1) cm{sup {minus}1}, and the Ru-Fe cyt c electron-transfer rate can be described with {lambda} = 1.2 eV and H{sub AB} = 0.03 cm{supmore » {minus}1}.« less

Ruthenium-modified cytochrome c: temperature dependence of the rate of intramolecular electron transfer

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRuthenium-modified cytochrome c: temperature dependence of the rate of intramolecular electron transferStephan S. Isied, Christa Kuehn, and Greg WorosilaCite this: J. Am. Chem. Soc. 1984, 106, 6, 1722–1726Publication Date (Print):March 1, 1984Publication History Published online1 May 2002Published inissue 1 March 1984https://doi.org/10.1021/ja00318a028RIGHTS & PERMISSIONSArticle Views174Altmetric-Citations67LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (597 KB) Get e-Alerts Get e-Alerts