Properties and Structure of the Compounds Formed between Cytochrome c and Nitric Oxide.

Abstract

The compound formed between ferricytochrome c and nitric oxide has been found to be diamagnetic. It is proposed to be a ferrocytochrome c nitrosyl compound from which the ferrocytochrome c nitric oxide compound can be obtained by alkalinization. Other haemoproteins behave similarly. The relationship between the optical absorption spectra of the nitrosyl, nitric oxide and carbon monoxide compounds of some ferrohaemoproteins is discussed. The haemlinked group of cytochrome c that is replaced by nitric oxide cannot be detected as a normal histidine imidazole by acid base titration. The possibility of a sterically hindered imidazole group has to be considered.