Heat inactivation and reactivation of broccoli (Brassica oleracea var. Italica) peroxidases.
Three peroxidase (POD) isoenzymes were purified from a soluble extract of broccoli stems. The acidic (A), neutral (N) and basic (B) POD were purified to homogeneity by using ion exchange and hydrophobic and gel filtration chromatography. N and B had molecular masses of approximately 43 kDa and A had molecular mass of 48 kDa by SDS-PAGE. pI was approximately 4, 5 and 8 for A, N and B, respectively. Optimum activity using guaiacol as the H donor were obtained at approximately pH 6 for both N and B and about pH 4 for A. All three of the purified isoenzymes are glycosylated. Reaction rate with various substrates, Km and amino acid composition were different among the isoenzymes. At 65