On the Nature of Glutamic Acid Decarboxylase in Wheat Embryos

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Abstract
Reaction kinetics of glutamic acid decarboxylase in wheat germ was studied. Michaelis-Menten constant of 0.025 [image], and an activation energy of 9100 calories for intact germ within temperature range of 21[degree] to 30[degree]C were obtained. Optimum temperature of decarboxylation of glutamate is 30 [degree]C, and that of O2 uptake mechanism about 40 [degree]C. RQ decreases constantly with increasing temperature from 21[degree]C to 50 [degree]C in wetted wheat germ. Isonicotinic acid hydrazide inhibits decarboxylation of glutamate to the same level that it reduces CO2 evolution from germ wetted with buffer containing no substrate. It is suggested that immediate CO2 evolution from wetted wheat germ is largely due to decarboxylation of free glutamic acid.