Yin Yongqi, Cheng Chao, Fang Weiming
College of Food Science and Technology, Yangzhou University Yangzhou Jiangsu 210095 People's Republic of China
RSC Adv. 2018 Jun 5;8(36):20456-20461. doi: 10.1039/c8ra03940b. eCollection 2018 May 30.
Glutamate decarboxylase (GAD) is the key enzyme in GABA shunt, which catalyzes the α-decarboxylation of glutamate to produce GABA. A specific inhibitor for GAD is convenient to study the dynamic balances of GABA metabolism in plants. The inhibitor of GAD in germinated fava beans was screened, and its inhibitory effect on the growth and GABA accumulation in fava beans during germination under hypoxia-NaCl stress was investigated. The inhibitory effect of aminoxyacetate for fava bean GAD was better than those of other chemicals, and it increased with the increase in concentration . After aminoxyacetate (5 mM) application for 4 days during germination, the GAD activity in germinating fava beans was significantly inhibited by more than 90% in both organs. Meanwhile, the growth of fava bean sprouts was also slightly suppressed. Moreover, the GABA contents decreased by 43.9% and 81.5% in a 4 day-old cotyledon and embryo, respectively, under aminoxyacetate treatment compared with that in the control. In summary, these results showed that aminoxyacetate can serve as a specific inhibitor of GAD in plants. At least 43.9% and 81.5% of GABA in germinating fava beans under hypoxia-NaCl stress were synthesized GABA shunt.
谷氨酸脱羧酶（GAD）是γ-氨基丁酸（GABA）支路中的关键酶，它催化谷氨酸的α-脱羧反应生成GABA。一种针对GAD的特异性抑制剂有助于研究植物中GABA代谢的动态平衡。筛选了发芽蚕豆中GAD的抑制剂，并研究了其在缺氧-氯化钠胁迫下对蚕豆发芽过程中生长和GABA积累的抑制作用。氨氧基乙酸对蚕豆GAD的抑制作用优于其他化学物质，且其抑制作用随浓度增加而增强。在发芽期间施用氨氧基乙酸（5 mM）4天后，发芽蚕豆两个器官中的GAD活性均被显著抑制超过90%。同时，蚕豆芽的生长也略有受到抑制。此外，与对照相比，在氨氧基乙酸处理下，4日龄子叶和胚中的GABA含量分别下降了43.9%和81.5%。综上所述，这些结果表明氨氧基乙酸可作为植物中GAD的特异性抑制剂。在缺氧-氯化钠胁迫下，发芽蚕豆中至少43.9%和81.5%的GABA是通过GABA支路合成的。
