Abstract:
Cytoch ro me c oxidase (ferrocytochrome c : 02
oxidoreductase ; EC 1.9. 3.1) is the terminal enzyme in the
mitochondrial electron transport chain, catalyzing the transfer of
electrons from ferrocytochrome c to molecular oxygen. The
effects of two large amphiphilic molecules .. valinomycin and
dibucaine upon the spectra of the isolated enzyme and upon the
activity of both isolated enzyme and enzyme in membrane
systems are investigated by using spectrophotometric and oxygen
electrode techniques.
The results show that both valinomycin and dibucaine
change the Soret region of the spectrum and cause a partial
inhibition in a concentration range higher than that in which they
act as ionophores. It is concluded that both valinomycin and
dibucain~ binding induce a conformational change of the protein
structure which modifies the spectrum of the a3 CUB centre and
diminishes the rate of electron transfer between cytochrome a
and the binuclear centre.
