Purification and characterization of a thermostable glutamate dehydrogenase from a thermophilic microorganism from Deception Island, Antarctica

作     者：Patricio A. Flores M. Freddy Boehmwald Jenny M. Blamey A. 

作者机构：Fundacion Cientifica y Cultural Biociencia Santiago Chile Jose Domingo Cafias 2280 Santiago Chile 775-0132 Universidad de Santiago Santiago Chile 

出 版 物：《Advances in Polar Science》 (极地科学进展（英文版）)

年 卷 期：2016年第27卷第1期

页      面：8-13页

学科分类：0710[理学-生物学] 071010[理学-生物化学与分子生物学] 07[理学] 

基　　金：supported by INNOVA-CORFO 07CN13PXT-64 Instituto Antártico Chileno (INACH) US Air Force Office of Scientific Research (AFOSR) 

主　　题：Antarctica glutamate dehydrogenase thermophile 

摘      要：Glutamate dehydrogenase （GDH） catalyzes the oxidative deamination of glutamate to a-ketoglutarate and ammonium ions. Currently the determination of ammonium and glutamate is carried out using a bovine GDH enzyme, which lacks optimal thermostability for long term storage at room temperature. From samples of Deception Island, Antarctica, we obtained the thermophilic bacteria PID 15 belonging to the Bacillus genera with high GDH specific activity. This new enzyme exhibited NAD＋ dependent activity and no activity was observed when NADP＋ was used. This enzyme shows a specific activity of 4.7 ***-1 for the oxidative deamination reaction and 15.4 U·mg-1 for the reduction of a-ketoglutarate. This enzyme has an optimum temperature of 65℃ and pH of 8.5 for the oxidative deamination. For the reduction of a-ketoglutarate, the optimum temperature is 60℃, with a pH of 8.0. One of the most important characteristics of this enzyme is its ability to retain more than 60% of its activity when it is incubated for 8 h at 65℃. The enzyme is also able to retain full activity when it is incubated for 48 d at 4℃ and over 80% of its activity when it is incubated at 25℃. Characterization of its kinetics suggests that it primarily catalyzes the formation of α-ketoglutarate. This enzyme has an important biological role in the catabolism of glutamate and may have some interesting biotechnological applications based on its thermostable properties.