Malate decarboxylation in isolated mitochondria from the crassulacean acid metabolism plant Sedum praealtum

摘要: Abstract Mitochondria isolated from the Crassulacean acid metabolism plant Sedum praealtum were demonstrated to decarboxylate added malate at basal rates of 30–50 μmol mg−1 original chlorophyll h−1. The rate could be stimulated markedly by addition ADP, oxaloacetic acid, an uncoupler oxidative phosphorylation, or NAD, with maximum 70–100 h−1 observed. These observed high enough account for a large proportion estimated decarboxylation in vivo. major products oxidation mitochondria most cases found pyruvate and CO2, indicating that these proceeds mainly through NAD malic enzyme rather than dehydrogenase. Under conditions employed little formed was further oxidized, suggesting fate other (conversion starch) this pyruvate. Malate partially purified inhibited NaHCO3. A possible physiological role is suggested inhibition as feedback control on enzyme.