Activities of carboxylation enzymes and products of 14CO2 fixation in photoautotrophically cultured cells

Abstract High activities of 14 CO 2 fixation into malate in the light were observed in photoautotrophically and photomixotrophically cultured cells of the C 3 plants Cytisus scoparius Link as well as Nicotiana tabacum var. Samsun. The percentages of 14 C in C 4 compounds (especially malate) were 44% of the total fixation in photoautotrophic cells and 41% of that in photomixotrophic cells at the end of the first 5 min. Measurements of the activities of enzymes related to CO 2 fixation indicated that the high labeling of malate in cultured green cells was associated with high PEP carboxylase activity.