Yu P H, Durden D A, Davis B A, Boulton A A
J Neurochem. 1987 Feb;48(2):440-6. doi: 10.1111/j.1471-4159.1987.tb04112.x.
The rate of transamination of gamma-aminobutryic acid (GABA) catalyzed by hog brain gamma-aminobutyrate aminotransferase was substantially reduced when the hydrogen at the gamma-carbon position was replaced by deuterium. The deuterium isotope effect of this reaction has been substantiated by fluorometric, radiometric, and mass spectrometric procedures and assessed kinetically. The ratios of Vmax of the nonlabeled substrate/Vmax of the deuterated substrate obtained under different conditions ranged from 6 to 7. This indicates that the cleavage of the hydrogen from the gamma-carbon is the rate-determining step in GABA transamination. Similar isotope effects have also been shown to occur in the peripheral system in vivo.
当猪脑γ-氨基丁酸转氨酶催化的γ-氨基丁酸（GABA）转氨作用中γ-碳位置的氢被氘取代时，其反应速率大幅降低。该反应的氘同位素效应已通过荧光法、放射性测量法和质谱法得到证实，并进行了动力学评估。在不同条件下获得的未标记底物的Vmax与氘代底物的Vmax之比在6至7之间。这表明从γ-碳上裂解氢是GABA转氨作用中的速率决定步骤。类似的同位素效应也已证实在体内外周系统中发生。
