Binding of copper(II) ion to cytochrome c

Publisher Website
Google Scholar
Abstract
Binding of aquacopper(II) ion to horse and tuna ferricytochrome c was investigated over the pH range 2-9. Between pH 4-7 the principal binding site for horse cytochrome has an intrinsic association constant of 1.8 .times. 104 1 mol-1 pKa of 6.5 .+-. 0.6 at 25.degree. C and ionic strength of 0.1. Binding to histidine 33 is consistent with this information, as well as with ESR, NMR and vissible absorption spectral data. Other sites also bind Cu, but with association constants at least a factor of 10 smaller. At high pH (> 8) further binding sites predominate.