Prabhakaran K, Harris E B, Kirchheimer W F
Arch Microbiol. 1983 Jul;134(4):320-3. doi: 10.1007/BF00407810.
Suspensions of Mycobacterium leprae purified from the organs (mostly spleen) of experimentally-infected armadillos (Dasypus novemcinctus, Linn) decarboxylated 1-(14C) glutamic acid liberating 14CO2. The reaction was pyridoxal phosphate-dependent and was inhibited by hydroxylamine, suggesting that it is a true amino acid decarboxylase. Loss of the activity at higher temperatures indicated the enzymatic nature of the reaction. Excess substrate or substrate analogs inhibited the decarboxylase whereas alpha-ketoglutarate and glutarate stimulated it. The activity was four times higher at pH 4.5 than at pH 6.8, suggesting that the enzyme is of microbial origin and not derived form the host cells. Armadillo spleen did not decarboxylate the amino acid. The Km value of the enzyme in the organisms was similar to that in Escherichia coli. The results reported here show that glutamate decarboxylase (EC 4.1.1.15) is an inherent metabolic activity of M. leprae, and might explain its unusual neural affinity. Glutamic acid is the most abundant amino acid occurring in the nerve tissue.
从实验感染的犰狳（九带犰狳，林奈）的器官（主要是脾脏）中纯化得到的麻风分枝杆菌悬液，能使1-(14C)谷氨酸脱羧，释放出14CO2。该反应依赖磷酸吡哆醛，并受到羟胺的抑制，这表明它是一种真正的氨基酸脱羧酶。在较高温度下活性丧失表明该反应具有酶促性质。过量的底物或底物类似物会抑制脱羧酶，而α-酮戊二酸和戊二酸则会刺激它。在pH 4.5时的活性比在pH 6.8时高四倍，这表明该酶源自微生物而非宿主细胞。犰狳脾脏不能使该氨基酸脱羧。该酶在生物体中的Km值与在大肠杆菌中的相似。此处报道的结果表明，谷氨酸脱羧酶（EC 4.1.1.15）是麻风分枝杆菌的一种固有代谢活性，可能解释了它对神经的特殊亲和力。谷氨酸是神经组织中含量最丰富的氨基酸。
