The ascorbate peroxidase (APX) system was studied in Capsicum annuum during fruit ripening. A large increase in organelle APX activity was found during chloroplast-chromoplast transition whereas only a slight difference was detected in total fruit extracts. On native gels, four different isoforms were found in total fruit extracts but the patterns for red and green fruit were quite different. In isolated organelles, six isozymes were found and a comparison of the patterns showed significant differences. A cDNA encoding a cytosolic APX was cloned and sequenced. The corresponding transcript was shown to increase 3-4-fold during fruit ripening.

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