THE THERMOSTABILITY OF PURIFIED ORANGES ISOPEROXIDASES

Soluble peroxidases were extracted from oranges (Citrus sinenses (L.) Osbeck). Small amounts of purified anionic and cationic isoperoxidases have been obtained by Rotofor (preparative isoelectric focusing) and ion-exchange chromatography. It has been shown that peroxidase activit y present in crude extracts of orange (juice, albedo and peel) are les s stable to heat than the enzymic activity of highly purified individu al orange peroxidases. It is suggested that this may be due to micro h eterogeneity in covalently bound oligosaccharide residues at the molec ular level.