INTERACTIONS OF CYTOCHROME C AND CYTOCHROME F WITH ASPARTIC ACID PEPTIDES

Cytochrome c (cyt c) and cytochrome f (cyt f) molecular recognition characters and their structural changes due to complex formation with negatively charged aspartic acid peptides (Aspptd's) have been studied. Changes in the absorption spectrum of cyt c in the Soret region were detected when Aspptd's, up to penta-Asp, were added to the cyt c solution. These changes were the same as those observed when cyt c interacted with plastocyanin (PC), indicating that Aspptd's interacted with cyt c in the same way as PC. Conformational changes of cyt c due to interaction with Aspptd's observed by resonance Raman spectroscopy were similar to those reported for cyt c when bound with its native partner, cytochrome c oxidase. Electrochemical measurements showed that the redox potential of cyt c and cyt f shifted to lower potentials by 7−20 mV upon Aspptd binding, showing the enhancement in the electron donor ability of both cyt c and cyt f upon complex formation with Aspptd. The changes in the absorption spectrum and re...