Spectral Relaxation of "Pulsed" Cytochrome c Oxidase

Abstract

Cytochrome c oxidase was isolated from bovine heart using the method of Yonetani (1961). The enzyme was transformed into the more active "pulsed" form by complete reduction followed by subsequent reoxidation as described by Orii and King (1976). The spectral relaxation of the metastable "pulsed" conformation was monitored between 400 and 500nm. T.he time resolved spectra were analyzed using Singular Value Decomposition (SVD) as described by Henry and Hofrichter (1992). The results obtained indicate that the "resting" to "pulsed" conformational transition is global, involving the contemporaneous decay of the two chromophores, cytochromes a and a3, within the enzyme and are discussed in terms of the putative bridging ligand between cytochrome a3 and CuB.