CHLOROPEROXIDASE FROM MUSA PARADISIACA STEM JUICE

摘要

Chloroperoxidase from Musa paradisiaca stem juice has been purified to homogeneity using concentration by ultrafiltration and anion exchange chromatography on DEAE cellulose. The purified enzyme gave single protein band in SDS-PAGE analysis corresponding to molecular mass of 43 kDa. The native PAGE analysis result also has given single protein band confirming the purity of the enzyme. The purified enzyme chlorinated and brominated monochlorodimedone,the substrate used for measuring the halogenating activity of chloroperoxidases. The Km and kcat values using monochlorodimedone as the substrate were 20 �M and 1.64 s-1 respectively giving kcat/Km value of 8.2 X 104 M-1s-1.The pH and temperature optima of the chlorinating activity were 3.0 and 25�C respectively. The Km values for peroxidase activity using pyragallol and H2O2 as the variable substrates were 89 �M and 120 �M respectively. The pH and temperature optima of the peroxidase activity using pyrogalllol as the substrate were the same as the pH and temperature optima of the halogenating activity. The peroxidase activity of the enzyme is competitively inhibited by sodium azide indicating that it is a hemeperoxidase different from non-heme peroxidases. Key words: Chloroperoxidase, Plant peroxidase, Musa paradisiaca, Metalloenzyme.