The effects of sugars on the development of hexose phosphorylating enzymes in the castor bean cotyledons

Abstract

The rate of development of soluble glucokinase and fructokinase activities in cotyledons isolated from castor bean seeds germinated for 36–48 hr is markedly increased by the presence of glucose, fructose or sucrose in the incubation medium. A similar effect is found for galactose on galactokinase activity. A certain degree of specificity in the effects of the different sugars on the three enzymes is observed. The rates of development of other enzyme activities such as phosphoglucomutase, glucose-6-phosphate dehydrogenase, aldolase, and NADP-dependent isocitrate dehydrogenase are not affected by the sugars. It is suggested that the effects of the sugars on kinase activities are due to enzyme induction of the type described in bacteria and lower organisms.