Desaspidin and CO(2) Fixation by Spinach Chloroplasts.

Baltscheffsky and de Kiewiet (1) proposed that desaspidin uncoupled photosynthetic phosphorylation in spinach chloroplasts. Arnon and coworkers (2, 3) have extended this work and on the basis of their finding that 1 ttm desaspidin inhibited cyclic phosphorylation completely while not affecting noncyclic phosphorylation, claim that desaspidin is a specific uncouipler at the site of cyclic phosphorvlation. Avron (6) challenged the specificity of desaspidin in uincoupling phosphorylation and concluded that its effectiveness was decreased under oxidizing conditions. In this commtunication, we compare the effects of desaspidin upon 14CO. fixatioin by spinach chloro-