School of Life Science and Technology, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan.
National Institute of Technology (KOSEN), Numazu College, Numazu, Shizuoka, Japan.
Biosci Biotechnol Biochem. 2021 Aug 25;85(9):1986-1994. doi: 10.1093/bbb/zbab122.
3-Isopropylmalate dehydrogenase (IPMDH) catalyzes oxidative decarboxylation of (2R, 3S)-3-isopropylmalate to 2-oxoisocaproate in leucine biosynthesis. In this study, recombinant IPMDH (HjIPMDH) from an extremely halophilic archaeon, Haloarcula japonica TR-1, was characterized. Activity of HjIPMDH increased as KCl concentration increased, and the maximum activity was observed at 3.0 m KCl. Analytical ultracentrifugation revealed that HjIPMDH formed a homotetramer at high KCl concentrations, and it dissociated to a monomer at low KCl concentrations. Additionally, HjIPMDH was thermally stabilized by higher KCl concentrations. This is the first report on haloarchaeal IPMDH.
3-异丙基苹果酸脱氢酶（IPMDH）在亮氨酸生物合成中催化（2R，3S）-3-异丙基苹果酸的氧化脱羧生成 2-氧代异己酸。本研究对来自极端嗜盐古菌日本盐杆菌 TR-1 的重组 IPMDH（HjIPMDH）进行了表征。HjIPMDH 的活性随 KCl 浓度的增加而增加，在 3.0 m KCl 时观察到最大活性。分析超速离心显示 HjIPMDH 在高 KCl 浓度下形成同源四聚体，在低 KCl 浓度下解离为单体。此外，较高的 KCl 浓度可使 HjIPMDH 热稳定性增强。这是关于嗜盐古菌 IPMDH 的首次报道。
