Moallic Claire, Dabonné Soumaila, Colas Bernard, Sine Jean-Pierre
Laboratoire de Biochimie, Unité de Biotechnologie, Biocatalyse et Biorégulation, CNRS-UMR 6204, Faculté des Sciences et Techniques, 2 rue de la Houssinière, BP 92208F44322, Nantes Cedex 3, France.
Protein J. 2006 Sep;25(6):391-7. doi: 10.1007/s10930-006-9025-4.
A gamma-glutamyltranspeptidase (GGT, E.C. 2.3.2.2) was isolated from a strain (A8) originating from Lake Bogoria (Kenya) and homologous with Bacillus pumilus. This GGT shows an optimal activity at pH 8.9 and 62 degrees C. The enzyme is thermostable up to 43 degrees C. The best reagent among the potential inhibitors was shown to be DON, which is an inhibitor highly specific for GGTs. Gly-Gly-Ala, Gly-Gly-Gly and Gly-Gly were identified as the best acceptors for the transpeptidation reactions catalyzed by the enzyme. The SDS-PAGE study revealed that the enzyme consists of two non-identical subunits (38,000 and 23,000). Only the large subunit was active when the enzyme was dissociated under denaturing conditions. The behavior of the native enzyme suggests that the active site of the large subunit is masked by the small subunit.
从源自肯尼亚博戈里亚湖的一株菌株（A8）中分离出一种γ-谷氨酰转肽酶（GGT，E.C. 2.3.2.2），它与短小芽孢杆菌同源。这种GGT在pH 8.9和62℃时表现出最佳活性。该酶在高达43℃时具有热稳定性。在潜在抑制剂中，最佳试剂是DON，它是一种对GGT具有高度特异性的抑制剂。甘氨酰-甘氨酰-丙氨酸、甘氨酰-甘氨酰-甘氨酸和甘氨酰-甘氨酸被确定为该酶催化的转肽反应的最佳受体。SDS-PAGE研究表明，该酶由两个不同的亚基（38,000和23,000）组成。当酶在变性条件下解离时，只有大亚基具有活性。天然酶的行为表明，大亚基的活性位点被小亚基掩盖。
