1crc
From Proteopedia
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CYTOCHROME C AT LOW IONIC STRENGTH
Overview
BACKGROUND: Cytochrome c is an integral part of the mitochondrial, respiratory chain. It is confined to the intermembrane space of, mitochondria, and has the function of transferring electrons between its, redox partners. Solution studies of cytochrome c indicate that the, conformation of the molecule is sensitive to the ionic strength of the, medium. RESULTS: The crystal structures of cytochromes c from several, species have been solved at extremely high ionic strengths of, near-saturated solutions of ammonium sulfate. Here we present the first, crystal structure of ferricytochrome c at low ionic strength refined at, 2.1 A resolution. In general, the structure has the same features as those, determined earlier. However, there are some differences in both backbone, and side-chain conformations in several areas. These areas coincide with, those observed by NMR and resonance Raman spectroscopy to be sensitive to, ionic strength. CONCLUSIONS: Neither ionic strength nor crystal-packing, interactions have much influence on the conformation of horse cytochrome, c. Nevertheless, some differences in the side-chain conformations at high, and low ionic strengths may be important for understanding how the protein, functions. Close examination of the gamma-turn (residues 27-29) conserved, in cytochromes c leads us to propose the 'negative classical' gamma-turn, to describe this unusual feature.
About this Structure
1CRC is a Single protein structure of sequence from Equus caballus with ACE and HEM as ligands. Full crystallographic information is available from OCA.
Reference
The low ionic strength crystal structure of horse cytochrome c at 2.1 A resolution and comparison with its high ionic strength counterpart., Sanishvili R, Volz KW, Westbrook EM, Margoliash E, Structure. 1995 Jul 15;3(7):707-16. PMID:8591047
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