the redox transitions of cytochrome a are coupled to ionization of at least two heme-linked acid-base groups of the enzyme with pk1 ( red ) in the acidic and pk2 ( ox ) in the alkaline regions of ph , whereas the ph dependence of e0 ' for cytochrome a3 fits to the model containing one hemi-linked group with a pkred in the acidic region .
C0030012
redox
C0010798
cytochrome