Proton magnetic resonances in cytochrome b2 core structural similarities with cytochrome b5

Abstract

The proton NMR spectra at 220 MHz of oxidised and reduced cytochrome b 2 core are presented and compared with the previously published NMR data on cytochrome b 5. Overall the experiments infer that quite striking structural similarities exist between the two proteins. In particular the heme coordination, details of the heme crevice, and the environment of the only tryptophanyl residue seem to be essentially the same. The NMR experiments provide a means to extend some of the detailed structural information available from the single crystal X-ray structure of cytochrome b 5 to cytochrome b 2, where at present only parts of the amino acid sequence are known and no atomic coordinates have as yet been reported.