Purification and Characterization of Catalase-2 from Deinococcus radiophilus

다국어 초록 (Multilingual Abstract)

A bifunctional catalase-peroxidase, designated catalase-2, of a UV resistant Deinococcus radiophilus was purified to electrophoretic homogeneity by both chromatograpic and electrophoretic methods. Its molecular weight was 310kDa and composed of a tetramer of 80 kDa subunits. The catalase-2 exerted its optical activity at 30℃ and around pH 9. Its Km value for H₂O₂was about 10 mM. It showed the typical ferric heme spectrum with maximum absorption at 403 nm which shifted to 419 nm in the presence of cyanide. The ratio of A403/A280 was 0.48. Fifty percent inhibition of the enzyme activity was observed at 4.6×10-6 7.7×10-6, and 3.0×10?/M of NaCN, NaN₃, and NH₂OH, respectively. The enzyme was thermostable and not sensitive to 3-amino-1,2,4-triazole. Treatment of the enzyme with ethanol-chloroform caused a partial loss(30%) of its activity. The catalase-2 was distinct form the Deinococcal bifunctional catalase-3 in a number of properties, particularly in its molecular structure and substrate affinity.