Light Activation of Ribulose Bisphosphate Carboxylase

Abstract

The development of methods of preparation of long wavelength ultraviolet lUt capable of activating ribulose bisphosphate carboxylase is reported. This preparation was obtained from tobacco (Nicotians tabacum) leaves which had reached about one-half maximum leaf weight. It was prepared at low ionic strength by use of mixed anion and cation exchange resins and buffers containing dimethylsulfoxide. The preparation is greatly enriched in fraction I protein to the point of apparent homogeneity. When assayed in the presence of saturating ribulose bisphosphate and sodium bicarbonate, the rate of carbon fixation is a linear function of long wavelength ultraviolet irradiation in the range of 20,000 to 30,000 ergs per square centimeter per second. Glutathione (5 (a) isolation and characterization of the light activation factor (LAF) (33); (b) the kinetics of the process of light activation (12,13,33,34); (c) the nature of the products of the reaction (13); and (d) the confirmation of the utility of the method of extraction (12). The process of elucidating the parameters of UV light activation of RuBPCase has taken over 10 years. The effect has been successfully reproduced by at least six researchers and this method has already been productively used in further work (13

Photoinactivation of Microcystis aeruginosa ribulose 1,5-bisphosphate carboxylase: Effects of endogenous and added sensitizers and the role of oxygen

“…Evidence has been presented for an indirect light effect, mediated via increased alkalinization of the chloroplast stroma and increased stromal Mg 2+ concentration [1]. Direct effects of light on the activation of the enzyme have also been reported [2,3]. In contrast, visible light has also been implicated in a photoinactivation of RuBP carboxylase in cyanobacterial cells [4,5] and in extracts from purple sulfur bacteria, cyanobacteria, green algae and higher plants in the presence of a sensitizer [6][7][8][9].…”

Light Activation of Enzymes

“…Kagawa [114] did not find this photoreactivation in uiuo and they suggested the effect in chloroplasts is possible because of inadvertent inactivation during isolation. For ribulose biphosphate carboxylase purified from tobacco leaves, near-UV light was effective and a light activation factor was associated with the enzyme [32]. In Lemna, light effects on synthesis of the large and small subunits were analyzed [145].…”