Abstract：HiTrapTM Blue HP affinity chromatography and DEAE-Sephadex ion-exchange chromatography were used to purify lactate dehydrogenase-A (LDH-A) from skeletal muscle of a male Tibetan sheep (Ovis aries) that lived in plateau. The relative activity of purified LDH-A was 100.94 U/mg protein, with purification times of 12.0. Only one band was observed when the purified LDH-A was separated with SDS-PAGE or native PAGE. Kinetic analysis showed that Michaelis constants (Km) value for reduced nicotinamide adenine denucleotide (NADH) was 0.022, and Km value for pyruvate was 0.444, which were significantly higher than those of rabbit. The optimal pH for the reduction of pyruvate was approximately 5.8. Oxalate and Hg2+ inhibited LDH-A activity, and Hg2+ was a reversible inhibitor of LDH-A.
