13C chemical shifts and13C–15N and13C–57Fe spin coupling constants as structural probes for haem environments.13C N.m.r. study of the binding of15N and13C labelled alkyl isocyanides to myoglobin and synthetic porphyrins

Abstract

A 13C n.m.r. study of 13C and 15N labelled alkyl isocyanides (R15N13C) bound to the heam iron(II) atom labelled with 57Fe in netural myoglobin and synthetic tetraphenyl- and octaethyl-porphyrin iron(II) shows that the iron-bound isocyanide 13C chemical shifts and 15N–13C coupling constants are sensitive to varioation of the R group and the presence of globin, while the one-bound 13C–57Fe coupling constant is not susceptible to these structural factors.