The assignment of proton resonances inboth redox states of a heme protein is necessary for the evaluation of pseudocontact shift data. Many new assignments are presented here for cytochrome b 5 particularly in the paramagnetic oxidised state, thereby allowing both the calculation of electronic g-tensor values with the magnetic axis orientation and a comparison of observed and calculated pseudocontact shifts utilising a computational procedure. The possible redox linked confonnational changes are found to be minimal in contrast with cytochrome c although the procedure additionally highlights aspects of the mobility of certain residues in cytochrome b 5. In this respect the residue Gly-42 appears mobile both by this method and by the observation from NMR spectra of a major and minor conformation in this region.
