Abstract:A cDNA encoding a putative dehydroascorbate reductase (DHAR) was cloned from sweet potato. The deduced protein showed a high level of sequence homology with DHARs from other plants (67 to 81%). Functional sweet potato DHAR was overexpressed and purified. The purified enzyme showed an active monomeric form on a 12% native PAGE. The proteinʼs half-life of deactivation at 50 °C was 10.1 min, and its thermal inactivation rate constant Kd was 6.4 × 10−2 min−1. The enzyme was stable in a broad pH range from 6.0−11.0 and in the presence of 0.8 M imidazole. The Km values for DHA and GSH were 0.19 and 2.38 mM, respectively.