Takano, Tsunehiro and Dickerson, Richard E. (1980) Redox Conformation Changes in Refined Tuna Cytochrome c. Proceedings of the National Academy of Sciences of the United States of America, 77 (11). pp. 6371-6375. ISSN 0027-8424. http://resolver.caltech.edu/CaltechAUTHORS:TAKpnas80
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Tuna ferrocytochrome c and ferricytochrome c have been refined independently at high resolution (1.5 angstrom and 1.8 angstrom) to crystallographic residual errors of 17.3% and 20.8%, respectively. Small but significant conformational differences are seen surrounding a buried water molecule that is hydrogen bonded to Asn-52, Tyr-67, and Thr-78. In the oxidized state, this water molecule is 1.0 angstrom closer to the heme and the heme has moved 0.15 angstrom out of its heme crevice; both changes lead to a more polar microenvironment for the heme. Chemical modification studies, patterns of evolutionary conservatism, structural differences in bacterial cytochromes, and x-ray studies all agree that the "active site" for cytochrome c is bounded by lysines 8, 13, 27, 72, 79, 86, and 87 (thus containing the evolutionary conservative 72-87 loop) and has the buried water molecule just below its surface and the opening of the heme crevice slightly to one side.
|Additional Information:||Copyright © 1980 by the National Academy of Sciences Communicated by Emanuel Margoliash, July 21, 1980 We thank George A. Carlson and Ben Conner for their help in various phases of crystal preparation, data collection, and data processing. This is Contribution No. 6231 from the Norman W. Church Laboratory of Chemical Biology, California Institute of Technology. This work was performed with the support of National Institutes of Health Grant GM-12121 and National Science Foundation Grant PCM 79-13959. 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.|
|Subject Keywords:||x-ray diffraction; electron transfer mechanism; protein conformation changes; buried water molecule; heme motion in protein|
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|Deposited On:||06 Nov 2006|
|Last Modified:||26 Dec 2012 09:15|
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