Interactions of cytochrome c peroxidase with lysine peptides

Structural change of Cytochrome c peroxidase (CcP) due to interaction with lysine peptides (Lysptds) has been studied by absorption spectra and measur ements on electron transfer between cytochrome c (cyt c) and CcP in the pre sence of Lysptd. Peaks were observed in the difference absorption spectrum of CcP between in the presence and absence of Lysptds, demonstrating a stru ctural perturbation of CcP, at least at its heme site, on interaction with Lysptd. The interaction between CcP and Lysptd was electrostatic, since no significant peak was detected in the difference absorption spectrum when 10 0 mM of NaCl was added to the solution. Lysptds competitively inhibited ele ctron transfer from cyt c to CcP, which indicated that they interacted with CcP at the same site as cyt c and would be models of the CcP interacting s ite of cyt c. (C) 2000 Academic Press.