Abstract
NADP:ferredoxin oxidoreductase (EC. 1.6.7.1.) isolated from a thermophilic blue-green alga, Synechococcus sp., was stable at temperatures up to 65°C. The diaphorase and cytochrome c reductase activities of the enzyme were low at 25°C but increased with elevated temperature to reach a maximum at about 60°C. The pH-profile of the diaphorase activity showed a peak at pH 9.0 at 55°C, whereas the activity was largely independent of pH at 25°C. High concentrations of NaCl suppressed activity at both high and low temperatures. In the cytochrome c reductase activity catalyzed by the enzyme, ferredoxin served as an electron carrier in a temperature-insensitive manner over a wide range of temperature. The results support the view that the optimum and the upper limiting temperatures for photosynthesis in this alga are related to thermal properties of proteins.
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Koike, H., Katoh, S. Thermal properties of NADP:ferredoxin oxidoreductase and ferredoxin isolated from a thermophilic blue-green alga. Photosynth Res 1, 163–170 (1980). https://doi.org/10.1007/BF00020595
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DOI: https://doi.org/10.1007/BF00020595