Carbon Dioxide Fixation in Isolated Kalanchoe Chloroplasts

Chloroplasts isolated from Kalanchoe diagremontiana leaves were capable of photosynthesizing at a rate of 5.4 mumoles of CO(2) per milligram of chlorophyll per hour. The dark rate of fixation was about 1% of the light rate. A high photosynthetic rate was associated with low starch content of the leaves. Ribose 5-phosphate, fructose 1,6-diphosphate, and dithiothreitol stimulated fixation, whereas phosphoenolpyruvate and azide were inhibitors. The products of CO(2) fixation were primarily those of the photosynthetic carbon reduction cycle.