GLUTAMIC-ACID DECARBOXYLASE AND GABA SHUNT IN SUPRAESOPHAGEAL GANGLION OF HONEY-BEE, APIS-MELLIFERA
GLUTAMIC-ACID DECARBOXYLASE AND GABA SHUNT IN SUPRAESOPHAGEAL GANGLION OF HONEY-BEE, APIS-MELLIFERA
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DOI：
10.1016/0022-1910(72)90075-3
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发表时间：
1972-01-01
影响因子：
2.2
通讯作者：
LARSEN, JR
中科院分区：
文献类型：
--
作者：
FOX, PM;LARSEN, JR
已证实蜜蜂大脑匀浆中存在l-谷氨酸脱羧酶。该酶在 pH 值 6·0 至 9·0 之间最活跃。在 pH 6·8K 和 Vmax 下，每克组织分别为 0·06 M 和 91μmoles/hr。蜜蜂酶被高浓度的 GABA 抑制，并且发现了一些底物被 1-谷氨酸抑制的证据。没有检测到对辅因子 5-磷酸吡哆醛的绝对需求。羟胺和对羟基汞苯甲酸盐的抑制分别是竞争性的和非竞争性的。酶的主要部分与在各种离心力下沉积的细胞颗粒部分结合。蔗糖梯度离心的结果表明，该酶没有与“突触体”大小的亚细胞颗粒结合。在蜜蜂大脑匀浆中也发现了能够将 GABA 代谢为琥珀酸的酶。本研究的结果与 1-谷氨酸和 GABA 作为可能的神经递质剂的作用进行了讨论。
The presence ofl-glutamic acid decarboxylase in homogenates of the honey-bee brain has been confirmed. The enzyme is most active between pH 6·0 to 9·0. At pH 6·8KmandVmaxwere 0·06 M and 91μmoles/hr per g tissue respectively. The honey-bee enzyme is inhibited by high concentrations of GABA and some evidence for substrate inhibition byl-glutamic acid was found. No absolute requirement for the cofactor, pyridoxal-5-phosphate, could be detected. Inhibition by hydroxylamine andp-hydroxymercuribenzoate were competitive and non-competitive respectively. The major portion of the enzyme was bound to cellular particulate fractions sedimenting in a wide range of centrifugal forces. Results of sucrose gradient centrifugations indicated that the enzyme was not bound to subcellular particles of ‘synaptosome’ size. Enzymes capable of metabolizing GABA to succinic acid were also found in honey-bee brain homogenates. The results of this study are discussed in relation to the rôle ofl-glutamic acid and GABA as possible neurotransmitter agents.