Partial characterization of peroxidase and polyphenol oxidase activities in blackberry fruits

A partial characterization of peroxidase (POD) and polyphenol oxidase (PPO) activities in blackberry fruits is described. Two cultivars of blackberry (Wild and Thornless) were analyzed for POD and PPO activities. Stable and h ighly active POD and PPO extracts were obtained using insoluble poly(vinylp yrrolidone) and Triton X-100 in 0.05 M sodium phosphate, pH 7.5, buffer. Bl ackberry POD and PPO activities have a pH optimum of 6.5, in a reaction mix ture of 0.2 M sodium phosphate. Optimal POD activity was found with 3% o-di anisidine. Maximum PPO activity was found with catechol (catecholase activi ty) followed by 4-methylcatechol. Polyacrylamide gel electrophoresis of bla ckberry extracts under non-denaturing conditions resolved in various bands. In the POD extracts of Wild fruits, there was only one band with a mobilit y of 0.12. In the Thornless POD extracts there were three well-resolved ban ds, with R-f values of 0.63, 0.36, and 0.09. Both the Wild and Thornless bl ackberry cultivars produced a single band of PPO, with R-f values of 0.1 fo r Wild and 0.06 for Thornless.