Strong Binding of Cytochrome c on the Envelope of Spinach Chloroplasts

Abstract

Yeast cationic ferricytochrome c was able to bind to the spinach (Spinacia oleracea) chloroplast envelope with a low affinity (Kd = 1.1 .mu.M). The total amount of low affinity binding sites was of the order of 50 nmol cytochrome c mg-1 protein. Apparently binding of ferricytochrome c to the envelope was electrostatic and the envelope membranes were strongly negatively charged. Addition of yeast ferricytochrme c to the envelope was electrostatic and the envelope membranes were strongly negatively charged. Addition of yeast ferricytochrome c to a preparation of intact washed chloroplasts (class I) induced strong chloroplast agglutination.