Purification and partial characterization of a low temperature responsive Mn-SOD from tea (Camellia sinensis (L.) O. Kuntze)

The manganese containing superoxide dismutase (Mn-SOD) was purified from a tea clone, TEENALI, which showed the lowest period of winter dormancy. Protein was purified using leaves of tea by ammonium sulfate precipitation, followed by column chromatography using DEAE-cellulose, and silica-based size exclusion chromatography on HPLC system. Upto 51-fold purification and a specific activity of 56.66 U/mg of protein was achieved, which yielded a single band upon denaturing PAGE. The enzyme had a native molecular weight of about 169 kDa, whereas a monomer with molecular weight of 43 kDa was found on SDS-PAGE suggesting it to be homotetramer. The purified enzyme had pH optima of 8.0. It exhibited a wide temperature range for its activity with optima at 0 degrees C suggesting its role in low temperature tolerance. The manuscript presents purification and characterization of high molecular weight Mn-SOD from tea and discusses its implication in tolerance of low temperature stress. (c) 2005 Elsevier Inc. All rights reserved.