A further investigation of the cytochrome b5-cytochrome c complex.
The interaction of reduced rabbit cytochrome b(5) with reduced yeast iso-1 cytochrome c has been studied through the analysis of (1)H-(15)N HSQC spectra, of (15)N longitudinal ( R(1)) and transverse ( R(2)) relaxation rates, and of the solvent exchange rates of protein backbone amides. For the first time, the adduct has been investigated also from the cytochrome c side. The analysis of the NMR data was integrated with docking calculations. The result is that cytochrome b(5) has two negative patches capable of interacting with a single positive surface area of cytochrome c. At low protein concentrations and in equimolar mixture, two different 1:1 adducts are formed. At high concentration and/or with excess cytochrome c, a 2:1 adduct is formed. All the species are in fast exchange on the scale of differences in chemical shift. By comparison with literature data, it appears that the structure of one 1:1 adduct changes with the origin or primary sequence of cytochrome b(5).
Banci
Lucia
L
Magnetic Resonance Center (CERM), University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Italy.
Bertini
Ivano
I
Felli
Isabella C
IC
Krippahl
Ludwig
L
Kubicek
Karel
K
Moura
José J G
JJ
Rosato
Antonio
A
D000818:Animals; D003198:Computer Simulation; D015786:Cytochromes b5 / Q000737:chemistry*; D045304:Cytochromes c / Q000737:chemistry*; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D025941:Protein Interaction Mapping; D011817:Rabbits
D045304:Cytochromes c; D015786:Cytochromes b5