Some enzymes of photosynthesis are active only in the light and others, only in the dark. This light/dark regulation is very important in determining plant productivity in important crop plants like maize. In studying this regulation, Dr. Chollet has discovered that a crucial light-regulated enzyme in corn leaves, pyruvate phosphate dikinase, appears to have two different enzyme activities. If substantiated, this would be intriguing and open up many new possibilities for enzyme regulation. This action funds purification studies of the plant enzyme and other biochemical studies to determine the role of phosphorylation in light/dark regulation.
