Studies on the intracellular location of enzymes of the photosynthetic carbon-reduction cycle.

Homogenates of dark-pretreated leaves yield two particulate fractions in density gradient centrifugation: one contains chlorophyll (chloroplasts) while a second fraction contains ribulose-1, 5-bisphophate carboxylase, NADP-dependent glyceraldehyde-3-phosphate dehydrogenase and catalase. Addition of a microbody-rich pellet to chloroplasts isolated from dark-pretreated plants largely enhances both oxygen evolution and CO2-fixation into organic compounds. The pathway of CO2 reduction may be part of a membrane system which, under suitable conditions, may separate from the chloroplast as a distinct cytoplasmic entity, having physical properties similar to those of microbodies.