In piezophilic microorganisms, enzymes are optimized to perform under high hydrostatic pressure. The two major reported mechanisms responsible for such adaptation in bacterial species are changes in amino acids in the protein structure, favoring their activity and stability under high-pressure conditions, and the possible accumulation of micromolecular co-solutes in the cytoplasm. Recently, the accumulation of glutamate in the cytoplasm of piezophilic Desulfovibrio species has been reported under high-pressure growth conditions. In this study, analysis of the effect of glutamate on the enzymatic activity of the thioredoxin reductase/thioredoxin enzymatic complex of either a piezosensitive or a piezophilic microorganism confirms its role as a protective co-solute. Analysis of the thioredoxin structures suggests an adaptation both to the presence of glutamate and to high hydrostatic pressure in the enzyme from the piezophilic strain. Indeed, the presence of large surface pockets could counterbalance the overall compression that occurs at high hydrostatic pressure to maintain enzymatic activity. A lower isoelectric point and a greater dipolar moment than that of thioredoxin from the piezosensitive strain would allow the protein from the piezophilic strain to compensate for the presence of the charged amino acid glutamate to interact with its partner.

在嗜压微生物中，酶被优化以在高静水压力下运行。导致细菌物种适应的两种主要机制是蛋白质结构中氨基酸的变化，有利于它们在高压条件下的活性和稳定性，以及小分子共溶质在细胞质中可能的积累。最近，谷氨酸在嗜压电脱硫弧菌细胞质中的积累已经报道了在高压生长条件下的物种。在这项研究中，分析谷氨酸对压敏或亲压微生物的硫氧还蛋白还原酶/硫氧还蛋白酶复合物的酶活性的影响证实了其作为保护性共溶质的作用。硫氧还蛋白结构的分析表明对谷氨酸的存在和来自亲压菌株的酶中的高流体静压的适应性。事实上，大表面口袋的存在可以抵消在高静水压力下发生的整体压缩，以保持酶活性。