ABSTRACT
Haemoproteins can be grouped into a variety of classes depending on their structures and functions. However, whatever their biological functions, all haemoproteins undergo redox reactions to yield Fe(II)/Fe(III) species provided they are supplied with redox partners operating at the necessary potentials. This chapter considers a range of topics concerning the rates at which haemoprotein-mediated electron transfers occur. They include haemoprotein structural dynamics, redox potentials, coupled electron-ion transfers, electron transfer within multiheaded haem-containing enzymes and the formation of reactive interprotein complexes involving cytochromes. The chapter also considers the structural features of haemoproteins and moves on to look at experimental and computational investigations of various factors that influence electron transfer rates. The electron donor–acceptor bonding properties of axial ligands are known to be influential in determining haem redox potentials. Intraprotein electron transfer has been a major area of study in recent years in order to determine values of β.
