CHARACTERIZATION OF CHILE PEPPER FRUIT PEROXIDASES DURING RIPENING

The enzymatic levels of peroxidases were found to increase in chile pe pper fruit during ripening. Previous work indicated that peroxidases w ere associated with the cuticle of the fruit where the enzymatic level s correlated with cuticle thickening and disease resistance. Fruit har vested at intervals throughout the growing season showed incremental i ncreases in total peroxidase enzyme levels and increased intensity in the activity of an acidic isozyme form of pi = 4.0 in polyacrylamide g els. Fast protein liquid chromatography on an anion-exchange column yi elded an acidic peroxidase enzyme activity in both green and red chile fruits. This peroxidase was purified 75-fold. The fraction of peroxid ase activity in a 28.3 kDa form increased from immature green to fully ripened red fruits, and it dominated in fully ripened red chile fruit s. This activity was markedly stable in in vitro, incubations up to 60 C for 15 min. Similar incubations above 70 degrees C decreased peroxi dase activity. The optimal pH for fruit peroxidase enzymatic activity was 6 with nearly equivalent stability over the range for 6-8. These r esults indicate that alternate forms of chile fruit peroxidases vary d uring fruit ripening, are stable at elevated temperatures, and demonst rate broad pH optima during the ripening stages.