Early Effects of Illumination on the Activity of Some Photosynthetic Enzymes

Abstract
Leaves of dark-grown corn (Zea mays) were illuminated for periods ranging from 3 min. to 12 hr. The changes in the activities of ribose-5-phosphate isomerase (I), ribulose-5-phosphate kinase (n), and ribulose-l,5-diphosphate carboxylase (HI) were followed. The activity of I did not change significantly until between 12 hr. and 24 hr. of illumination. An increase in II activity occurred after a lag of about 6 hr. The increase in III activity began after 3 min. of illumination and increased until after 3 to 6 hr. in the light, after which it began to decline. The increases in these enzymes appear to be the result of protein synthesis.
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