Photosynthetic activity of isolated chloroplasts.

Abstract

The concept of photosynthesis that emerged from work with isolated chloroplasts differs from the conventional view of photosynthesis as a process of CO2 assimilation. Photosynthesis appears to be first and foremost a process for converting the radiant energy of sunlight into chemical energy. This conversion is directly linked to cyclic and noncylic photophosphorylation, which involve the esterification of inorganic phosphate and the reduction of the iron protein, ferredoxin. The first stable, chemically defined products of the energy conversion process in photosynthesis proved to be not intermediates of carbon assimilation but ATP and reduced ferredoxin. The basic facts of cyclic and noncyclic photophosphorylation are now well established but the hypotheses invoked to explain their mechanisms are subject to change as further refinements of experimental techniques bring new facts to light.