Shima S, Hérault D A, Berkessel A, Thauer R K
Institut für Organische Chemie, Universität Köln, Greinstrasse 4, D-50939 Köln, Germany.
Arch Microbiol. 1998 Nov;170(6):469-72. doi: 10.1007/s002030050669.
Enzymes involved in methane formation from carbon dioxide and dihydrogen in Methanopyrus kandleri require high concentrations (> 1 M) of lyotropic salts such as K2HPO4/KH2PO4 or (NH4)2SO4 for activity and for thermostability. The requirement correlates with high intracellular concentrations of cyclic 2,3-diphosphoglycerate (cDPG; approximately 1 M) in this hyperthermophilic organism. We report here on the effects of potassium cDPG on the activity and thermostability of the two methanogenic enzymes cyclohydrolase and formyltransferase and show that at cDPG concentrations prevailing in the cells the investigated enzymes are highly active and completely thermostable. At molar concentrations also the potassium salts of phosphate and of 2,3-bisphosphoglycerate, the biosynthetic precursor of cDPG, were found to confer activity and thermostability to the enzymes. Thermodynamic arguments are discussed as to why cDPG, rather than these salts, is present in high concentrations in the cells of Mp. kandleri.
坎氏甲烷嗜热菌中参与由二氧化碳和氢气生成甲烷的酶需要高浓度（>1M）的促溶盐，如磷酸氢二钾/磷酸二氢钾或硫酸铵，以保持活性和热稳定性。这种需求与这种嗜热生物细胞内高浓度的环化2,3 - 二磷酸甘油酸（cDPG；约1M）相关。我们在此报告了环化二磷酸甘油酸钾对两种产甲烷酶环水解酶和甲酰转移酶活性和热稳定性的影响，并表明在细胞中普遍存在的cDPG浓度下，所研究的酶具有高活性且完全热稳定。在摩尔浓度下，还发现磷酸钾盐和2,3 - 二磷酸甘油酸（cDPG的生物合成前体）的钾盐能赋予这些酶活性和热稳定性。文中讨论了关于为什么在坎氏甲烷嗜热菌细胞中cDPG而非这些盐以高浓度存在的热力学论据。
