PARTIAL-PURIFICATION AND THERMAL CHARACTERIZATION OF PEROXIDASE FROM OKRA (HIBISCUS-ESCULENTUM)

Thermal characteristics and substrate specificity of peroxidase (POX) from okra were determined. Crude POX was separated into eight fraction s (P1-P8) by DEAE-cellulose chromatography. Heat inactivation of POX w as biphasic and fitted to a first-order kinetic model. Inactivation ra tes of crude POX and eight POX fractions at 70 degrees C varied betwee n (63.499 and 123.809) x 10(-2) min(-1) for the heat-labile fractions and (11.255 and 31.441) x 10(-2) min(-1) for the heat-stable fractions . Activation energies for the inactivation of crude extract were 37.0 kcal mol(-1) with a z-value of 13.8 degrees C for the heat-labile frac tion and 37.8 kcal mol(-1) with a z-value of 13.5 degrees C for the he at-stable fraction. Optimum temperatures were between 30 and 35 degree s C for the crude extract, 60 degrees C for P1-P5 fractions, and more than 65 degrees C for P6-P8 fractions. Among substrates, guaiacol was oxidized primarily by P1-P6 fractions; whereas, pyrogallol and catechi n were preferred by P7 and P8, respectively.