Premium
EFFECTS OF BLUE‐LIGHT ON PYRUVATE KINASE ACTIVITY DURING CHLOROPLAST DEVELOPMENT OF UNICELLULAR GREEN ALGAE*
Author(s) -
Ruyters Günter
Publication year - 1982
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1982.tb03837.x
Subject(s) - chlorella , pyruvate kinase , chloroplast , mutant , chlorella vulgaris , light intensity , biochemistry , scenedesmus , chlorophyll , photosynthesis , phosphoenolpyruvate carboxykinase , biology , substrate (aquarium) , algae , enzyme , biophysics , chemistry , botany , glycolysis , ecology , physics , gene , optics
— In analysing the stimulating effect of blue‐light on respiration and carbohydrate degradation of green algae, the author demonstrated a dual light‐effect on pyruvate kinase (E.C. 2.7.1.40.) of the chlorophyll‐free, carotenoid‐containing mutant. No. 20, of Chlorella vulgaris. This dual effect consists first in an enhancement of the maximal velocity of the enzyme reaction, and second in an increase in the affinity towards the substrate phosphoenolpyruvate. Attempts to elucidate the importance of this enhanced enzyme activity led to the assumption that it might be seen in correspondence with chloroplast development. To support this assumption, the influence of short‐wave visible radiation on pyruvate kinase of Scenedesmus C‐2A' was investigated, a mutant, yellow in the dark, but forming a functioning chloroplast under blue‐light conditions. Indeed, it could be shown that in this organism the substrate affinity of pyruvate kinase is increased during the blue‐light‐mediated greening process and that the dependencies of this blue‐light effect on the age of culture, light intensity, and duration of light treatment are in good agreement with the corresponding data for the Chorella mutant. The results thus support the assumption that the light‐enhancement of pyruvate kinase in the yellow Chlorella mutant. No. 20, may be a remaining part of the blue‐light‐controlled chloroplast development found in some other algae and mutants like e.g. Scenedesmus C‐2A'.