Influence of blue light on the activity of phosphofructokinase in Chlorella kessleri |
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Authors: | Norbert Grotjohann Wolfgang Kowallik |
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Affiliation: | Fakultät für Biologie, Univ. Bielefeld, Postfach 8640, D-4800 Bielefeld. FRG. |
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Abstract: | In crude extracts of Chlorella kessleri Fott and Novákóva cells grown autotrophically in white light the activity of phosphofructokinase (PFK, EC 2.7.1.11) is 62.9 ± 1.5 nmol (mg protein)−1 min−1 under optimized test conditions. It is greatly increased in red [88.3 ± 1.8 nmol (mg protein)−1 min−1], but somewhat decreased [57.0 ± 0.5 nmol (mg protein)−1 min−1] in blue light of equal productivity. Mixtures of blue and red light yield the low activity as long as blue light represents at least 35% of the total quantum fluence rate. The rough wavelength dependence of the counteracting effect of short wavelength light on the increasing effect of red light exhibits a broad peak at 460 nm, reminiscent of action spectra of the blue/UV photoreceptors(s). Upon transfer of red light-grown cells to blue light, the decrease develops slowly within 72 h; it cannot be prevented by 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU). Since there is less carbohydrate in blue than in red light-exposed cells, correlations between biosynthesis of PFK and level of carbohydrate are discussed, based on the assumption that red light decreases and/or blue light increases the transport of metabolites across the chloroplast envelope. |
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Keywords: | blue/UV-photoreceptor Chlorella kessleri phosphofructokinase |
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