Functional divergence and catalytic properties of dehydroascorbate reductase family proteins from Populus tomentosa

摘要: Dehydroascorbate reductase (DHAR) is a key enzyme in the ascorbate–glutathione cycle that maintains reduced pools of ascorbic acid and serves as an important antioxidant. In this study, to investigate functional divergence plant DHAR family catalytic characteristics glutathione binding site (G-site) residues proteins, we cloned three genes (PtoDHAR1/2/3) from Populus tomentosa predicted G-site residues. PtoDHAR1 protein was localized chloroplast, while PtoDHAR2/3 proteins showed cytosolic localizations. Three different enzymatic activities, apparent kinetic characteristics, optimum T m pH profiles, indicating their divergence. Cys20, Lys8, Pro61, Asp72 Ser73 PtoDHAR2 were based on N-terminal amino sequence identity available crystal structures S-transferases. The biochemical functions these are examined study through site-directed mutagenesis. aforementioned five critical components active sites contribute enzyme’s activity. Pro61 also responsible for maintaining proper structure. This provides new insights into properties proteins.