@article{oai:repo.qst.go.jp:00078401,
 author = {Arai, Shigeki and Shibazaki, Chie and Shimizu, Rumi and Adachi, Motoyasu and Ishibashi, Matsujiro and Tokunaga, Hiroko and Tokunaga, Masao and Shigeki, Arai and Chie, Shibazaki and Rumi, Shimizu and Motoyasu, Adachi},
 issue = {1},
 journal = {Acta Crystallographica section D},
 month = {Jan},
 note = {AbstractThioredoxin (TRX) is an important antioxidant against oxidative stress. TRX from Halobacterium salinarum NRC-1 (HsTRX-A), which has the highest acidic residue content ([Asp + Glu] / [Arg + Lys + His] = 9.0) among known TRXs, was chosen to elucidate a catalytic mechanism and evolutionary characteristics associated with haloadaptation. X-ray crystallographic analysis revealed that the main chain structure of HsTRX-A is similar to those of homologous TRXs; e.g., root-mean-square deviations for Cα atoms were <2.3 Å for the extant archaeal TRXs and <1.5 Å for the resurrected Precambrian TRXs. The density of negative charges at the molecular surface (0.0035 Å-2) and the structural flexibility of the long N-terminal coil (Arg1–Pro16) of HsTRX-A were higher than those of homologous TRXs and should improve solubility and haloadaptivity. Circular dichroism measurement indicated that the structure of HsTRX-A is highly flexible and that a high salt concentration (~4 M NaCl) is required for structural stabilization. A unique water network was located near the active-site residues (Cys47 and Cys50) in HsTRX-A, which may enhance the proton transfer required for reduction of substrates under a high-salt environment. A structural inspection of TRXs revealed that helix α1 in TRXs elongated during evolution from LACA-TRX (the last archaeal common ancestor TRX) to extant archaeal TRXs, including HsTRX-A. These observations offer insights into molecular evolution for haloadaptation and potential applications in halophilic protein-related biotechnology.},
 pages = {73--84},
 title = {Catalytic mechanism and evolutional characteristics of thioredoxin from Halobacterium salinarum NRC-1},
 volume = {76},
 year = {2020}
}