Change in charge of an unvaried heme contact residue does not cause a major change of conformation in cytochrome c.
The structure of the Ala38 variant of yeast iso-1-cytochrome c, in which the previously unchanged Arg38 has been replaced, has been characterised by NMR. The NMR data indicate that the structure of the Ala38 variant is very similar to that of the wild type protein. In particular, the heme environment and interactions of the heme macrocycle are shown to be preserved. Analysis of the chemical shift perturbations to the resonances of Ile35 is shown to be consistent with the change in charge at position 38. The only significant area of conformational change detected was at residues 39 and 58, close to the site of modification. Therefore the redox potential change accompanying the modification [1988, Biochemistry 28, 3188-3197] appears to be a direct consequence of the altered side-chain of residue 38 and not a result of secondary conformational changes induced by the modification.
Thurgood
A G
AG
Centre for Metalloprotein Spectroscopy and Biology, School of Biological Sciences, University of East Anglia, Norwich, UK.
Pielak
G J
GJ
Cutler
R L
RL
Davies
A M
AM
Greenwood
C
C
Mauk
A G
AG
Smith
M
M
Williamson
D J
DJ
Moore
G R
GR
D000409:Alanine / Q000737:chemistry; D001120:Arginine / Q000737:chemistry; D003574:Cytochrome c Group / Q000737:chemistry*; D004563:Electrochemistry; D006418:Heme / Q000737:chemistry*; D007532:Isoleucine / Q000737:chemistry; D007930:Leucine / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D016296:Mutagenesis; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000032:analysis
D003574:Cytochrome c Group; D007532:Isoleucine; D006418:Heme; D001120:Arginine; D007930:Leucine; D000409:Alanine