Capacity of enzymes of the euphorbiacea Aleurites montana involved in CO2-fixation, compared to plants having C-3-, C-4- and Crassulacean acid metabolism

Grotjohann N, He P, Schmid GH. Capacity of enzymes of the euphorbiacea Aleurites montana involved in CO2-fixation, compared to plants having C-3-, C-4- and Crassulacean acid metabolism. ZEITSCHRIFT FUR NATURFORSCHUNG C-A JOURNAL OF BIOSCIENCES. 2000;55(5-6):383-391.Capacities of phosphoenolpyruvate carboxylase (PEP-Co), ribulose bisphosphate carboxylase (Rubisco), NADP(+) malic enzyme (ME) and of malate dehydrogenase (MDH) were measured in the Euphorbiacea Aleurites montana, grown under 700 ppm CO2 for four weeks prior to enzyme extraction. For comparison Bryophyllum diagremontiana (CAM), Saccharum officinarum (C-4) and Capsicum frutescens (C-3) were treated in the same way. PEP-Co capacity of Aleurites was in the range of 12-, that of Capsicum approx. 26 nmol x min(-1) x mg protein(-1), without significant influence of the light period or CO2-treatment. In contrast, the activity of the enzyme from Saccharum was, depending on the duration of light, 160- respectively 96 times higher than that of the tung-oil tree. In Bryophyllum a rather low activity in the morning was increased during the day to approx. 230 nmol x min(-1) x mg protein in plants grown in the greenhouse and to approx. 115 nmol x min(-1) x mg protein(-1) in those from the growth chamber. Malate was hardly detectable in extracts of Aleurites, whereas it was high in Bryophyllum, depending on the light period. The ratio of average PEP-Co to Rub-Co capacity was high for the CAM-plant (20:1), somewhat lower for sugar cane (10:1), but almost at equality for Aleurites (0.9:1) and chilli (0.8:1). For the NADP(+) malic enzyme, low capacity (20 to 28 nmol x min(-1) x mg protein(-1)) was found for Aleurites and for Capsicum, whereas it was 10 to 17 times higher in Saccharum. In Bryophyllum, the activity was up to 80 nmol x min(-1) x mg protein(-1), dependent on light period. MDH capacity was extremely high in all plants investigated. Highest rates (10-20 mu mol x min(-1) x mg protein(-1)), were obtained for Bryophyllum, followed by sugar cane and Capsicum with 5-8 mu mol x min(-1) x mg protein. Again, the lowest capacity was found in extracts of Aleurites with approx. 1.3 to 1.6 pmol x min(-1) x m protein(-1). Thus, in Aleurites montana no indication for C-4- Or Crassulacean acid metabolism was obtained. Therefore, the earlier observed very efficient uptake of CO2 cannot be explained by a high expression of the PEP-Co protein, known to occur in CAM- and C-4-plants

INFLUENCES OF BLUE AND RED-LIGHT ON THE PHOTOSYNTHETIC APPARATUS OF CHLORELLA-KESSLERI - ALTERATIONS IN PIGMENT-PROTEIN COMPLEXES

Grotjohann N, RHO MS, KOWALLIK W. INFLUENCES OF BLUE AND RED-LIGHT ON THE PHOTOSYNTHETIC APPARATUS OF CHLORELLA-KESSLERI - ALTERATIONS IN PIGMENT-PROTEIN COMPLEXES. BOTANICA ACTA. 1992;105(3):168-173.In white light of 33.2-mu-mol . m-2 . s-1 oxygen evolution of Chlorella kessleri is about 30 % higher after growth in blue light than after growth in red light of the same quantum fluence rate. When determined by the light-induced absorbance change at lambda-820 nm, blue light-adapted cells possess about 60 % more reaction centres per total chlorophyll in photosystem II. Correspondingly, the cells exhibit about 30 % more Hill activity of PS II. Conversely, red light-adapted cells contain relatively more reaction centres and higher electron flow capacities of photosystem I. The distribution of total chlorophyll among the pigment-protein complexes, CPI, CPIa, CPa, and LHC II, corresponds to these data. There is more chlorophyll associated with the light-harvesting complex of PS II, LHC II, in cells under blue light conditions, but more chlorophyll bound to both complexes of PS I, CPI and CPIa, in cells under red light conditions. The respective ratios of chlorophyll a/chlorophyll b of all complexes are identical for blue and red light-adapted cells. This results in a higher relative amount of chlorophyll b in blue light-adapted cells. Total carotenoids per total chlorophyll are increased by 20 % in red light-adapted cells. Their distribution among the pigment-protein complexes is unknown, however the ratios of lutein, neoxanthin and violaxanthin extractable from LHC II are different in blue (32.1: 35.9: 32.0) and in red (51.4: 26.7: 21.9) light-adapted cells