A Caltech Library Service

Preparation and characterization of pentaammineruthenium-(histidine-83)azurin: Thermodynamics of intramolecular electron transfer from ruthenium to copper

Margalit, Ruth and Kostić, Nenad M. and Che, Chi-Ming and Blair, David F. and Chiang, Huey-Jenn and Pecht, Israel and Shelton, Joan B. and Shelton, J. Roger and Schroeder, Walter A. and Gray, Harry B. (1984) Preparation and characterization of pentaammineruthenium-(histidine-83)azurin: Thermodynamics of intramolecular electron transfer from ruthenium to copper. Proceedings of the National Academy of Sciences of the United States of America, 81 (20). pp. 6554-6558. ISSN 0027-8424. PMCID PMC391964. doi:10.1073/pnas.81.20.6554.

PDF - Published Version
See Usage Policy.


Use this Persistent URL to link to this item:


The reaction between a5RuH2O2+ (a is NH3) and Pseudomonas aeruginosa azurin at pH 7, followed by oxidation, yields a5Ru(His-83)3+-azurin(Cu2+) as the major product. Spectroscopic measurements (UV-visible, CD, EPR, and resonance Raman) indicate that the native structure is maintained in the modified protein. The site of ruthenium binding (His-83) was identified by peptide mapping. The a5RuHis/Cu ratio in the modified protein, determined from the EPR spectrum, is 1:1, and the reduction potentials (vs. normal hydrogen electrode, pH 7.0, 25 degrees C) are blue copper (Cu2+/1+), 320 ± 2 mV; a5Ru(His-83)3+/2+, 50 ± 10 mV. From measurements of the reduction potentials at several temperatures in the 5-40 degrees C range, delta-H degrees for intramolecular Ru2+ --> Cu2+ electron transfer was estimated to be -12.4 kcal mol(-1) (1 cal = 4.184 J). Analysis of kinetic data in light of the electron transfer exothermicity indicates that the reorganizational enthalpy of the blue copper site can be no larger than 7.1 kcal mol(-1).

Item Type:Article
Related URLs:
URLURL TypeDescription
Gray, Harry B.0000-0002-7937-7876
Additional Information:© 1984 by the National Academy of Sciences. Contributed by Harry B. Gray, May 29, 1984. We thank Stephen Mayo for Fig. 3, Vance Morgan for help with the CD measurements, Tin Wu Tang for assistance with cyclic voltammetry, and Ting Lin Kao for a sample of Na[Co(EDTA)]. Helpful comments were provided by Walther Ellis, Karl Freed, Michel Goldberg, Brian Hoffman, John Hopfield, Noel Hush, Sven Larsson, George McLendon, Bo Malmstrom, and Rudy Marcus. This research was supported by National Institutes of Health Grants AM19038 (H.B.G.) and HL02558 (W.A.S.). This is contribution no. 7033 from the Arthur Amos Noyes Laboratory. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.
Funding AgencyGrant Number
Subject Keywords:ruthenium-histidine binding, protein modification, blue copper, oxido-reduction, reorganization energy
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Arthur Amos Noyes Laboratory of Chemical Physics7033
Issue or Number:20
PubMed Central ID:PMC391964
Record Number:CaltechAUTHORS:MARpnas84
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:955
Deposited By: Tony Diaz
Deposited On:15 Nov 2005
Last Modified:08 Nov 2021 19:06

Repository Staff Only: item control page