Changing Kinetic Properties of Fructose-1,6-bisphosphatase from Pea Chloroplasts during Photosynthetic Induction

Abstract

After dark-light transitions, there is a delay in photosynthetic CO2 fixation by isolated pea chloroplasts in the range of some minutes. To assess the physiological significance of light modulation of enzyme activity in the control of induction, estimates were made of the kinetic parameters of fructose-1,6-bisphosphatase immediately upon release from pea chloroplasts in the dark and after illumination for various time periods. The Michaelis constant for fructose-1,6-bisphosphate decreased and maximal velocities increased during induction. Light activation of this enzyme may be one of the factors contributing to the overcoming of the lag period in photosynthetic CO2 fixation.