Isolation, characterization and immune localization of orange fruit acetyl esterase.

Acetyl esterase (AE) has been purified to homogeneity from orange peels. The purification steps included cation exchange chromatography and gel filtration. The enzyme has affinity for triacetin and sugar beet pectin with K-M of 39 mM and K-M of 26 mg/ml, respectively. AE has a MW of 42 kD and is a monomer. The isoelectric point is at pH > 9. Immuno localization using polyclonal antibodies raised against AE showed that AE was widely distributed in orange fruit but with more intensive immunological detection in the outer part of the peels e.g. albedo and flavedo and in the segments (juice vesicles). The results indicate that AE is located at the site where the major fraction of pectin is deposited.