The source of heterogeneity in the heme vicinity of ferricytochrome c.
Heterogeneity in the heme vicinity of ferricytochrome c was reported to be detectable by a split of the NMR signal of the heme methyl 3 group [P.D. Burns and G.N. La Mar, J. Am. Chem. Soc. 101 (1979) 5844]. Using cytochrome c mutants and computer simulations of the native and mutated cytochromes, the source of this heterogeneity is found to originate from the His-33 residue motions. The H33F mutation abolished the NMR split and computer simulations of the H33F mutant revealed a narrower distribution of fluctuations of the radius of gyration, suggesting a more rigid structure due to the mutation. The stabilization of the mutant was further demonstrated by a reduction in the H33F mutant of 4 Kcal/mol in the calculated interaction energy between residue 33 and the rest of the cytochrome, in keeping with known experimental results.
Taler
G
G
School of Chemistry, Sackler Faculty of Exact Sciences, Tel Aviv University, Israel.
Becker
O M
OM
Navon
G
G
Qin
W
W
Margoliash
E
E
Schejter
A
A
D000818:Animals; D003198:Computer Simulation; D003574:Cytochrome c Group / Q000737:chemistry* / Q000235:genetics; D004355:Drug Stability; D006418:Heme / Q000737:chemistry; D006639:Histidine / Q000737:chemistry; D006736:Horses; D009682:Magnetic Resonance Spectroscopy; D017354:Point Mutation; D011487:Protein Conformation; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D013816:Thermodynamics
D003574:Cytochrome c Group; D011994:Recombinant Proteins; D006418:Heme; D006639:Histidine