NMR study of the interaction between cytochrome b5 and cytochrome c: Observation of a ternary complex formed by the two proteins and [Cr(en) 3] 3+

Abstract

The interaction between horse cytochrome c and the tryptic fragment of bovine liver microsomal cytochrome b 5 in the absence and presence of [Cr(ethylenediamine) 3]Cl 3 was studied by 1H NMR spectroscopy. The protein-protein interaction region on cytochrome b 5 was found to be different from the [Cr(en) 3] 3+ binding region. The solvent-exposed propionate-bearing edge of the haem of cytochrome b 5 is accessible to [Cr(en) 3] 3+ in the interprotein complex.