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首页> 外文期刊>Biochimica et biophysica acta: BBA: International journal of biochemistry, biophysics and molecular biololgy. Proteins and Proteomics >Compatible solute effects on thermostability of glutamine synthetase and aspartate transcarbamoylase from Methanococcus jannaschii
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Compatible solute effects on thermostability of glutamine synthetase and aspartate transcarbamoylase from Methanococcus jannaschii

机译：溶质对詹氏甲烷球菌谷氨酰胺合成酶和天冬氨酸转氨甲酰酶热稳定性的影响

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摘要

Methanococcus jannaschii accumulates alpha- and beta-glutamate as osmolytes. The effect of these and other solutes on the thermostability of two multisubunit metabolic enzymes from M. jannaschii, aspartate transcarbamoylase catalytic trimer (ATCase C-3) and glutamine synthetase (GS), has been measured and compared to solute effects on bacterial mesophilic counterparts in order to explore if osmolytes accumulated by each organism can preferentially stabilize the proteins to thermal unfolding. For both ATCase enzymes and for the B. subtilis GS, the solutes normally accumulated by the organism were very effective in protecting the enzyme from losing activity at high temperatures, although solute effects on loss of secondary structure did not necessarily correlate with this thermoprotection of activity. The recombinant M. jannaschii GS exhibited quite different behavior. The pure enzyme had a thermal unfolding transition with a midpoint temperature (T-m) less than 60 degrees C, well under the growth temperature of the organism (85 degrees C). None of the small molecule solutes tested (including the K+-glutamate isomers accumulated by M. jannaschii) significantly stabilized the protein to incubation at 85 degrees C. Instead, protein-protein interactions, as illustrated by E. coli GroEL or ribosomal protein L2 stabilization of GS, appeared to be the dominant factor in stabilizing this archaeal enzyme at the growth temperature. (c) 2005 Elsevier B.V All rights reserved.
机译：詹氏甲烷球菌累积α-和β-谷氨酸作为渗透压剂。已测量了这些和其他溶质对詹氏甲烷球菌的两个多亚基代谢酶，天冬氨酸转氨甲酰酶催化三聚体（ATCase C-3）和谷氨酰胺合成酶（GS）的热稳定性的影响，并将其与溶质对细菌嗜温性对应物的影响进行了比较。为了探究每种生物体积累的渗透压是否可以优先稳定蛋白质使其热解折叠。对于ATCase酶和枯草芽孢杆菌GS而言，尽管溶质对二级结构丧失的影响并不一定与此活性的热保护相关，但通常由生物体积累的溶质在防止酶在高温下丧失活性方面非常有效。 。重组詹氏甲烷球菌GS表现出完全不同的行为。纯酶的热解折叠转变的中点温度（T-m）低于60摄氏度，远低于生物体的生长温度（85摄氏度）。测试的小分子溶质（包括詹氏甲烷八叠球菌积累的K +-谷氨酸异构体）均无法显着稳定蛋白质使其在85摄氏度下温育。相反，蛋白质-蛋白质相互作用（如大肠杆菌GroEL或核糖体蛋白质L2稳定化所说明） GS，似乎是在生长温度下稳定该古细菌酶的主要因素。 （c）2005 Elsevier B.V保留所有权利。

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