Optimum Temperature And Thermal Stability Of Crude Polyphenol Oxidase In Greensmall Cherry Tomatoe (Solanum Lycopersycum)

Polyphone oxidase (PPO) (EC.1.14.18.1) catalyzes the hydroxylation of monophenols to o-diphenols and the oxidation of o-diphenols to o-quinones leading to browning in plants. Polyphenol oxidase activity was detected in green small cherry tomato (Solanum Lycopersicum) cultivated in Kurdistan(Iran). In this study, the effect of temperature on activity in presence of catechol and pyrogallol was investigated.For polyphenol oxidase activity in green small cherry tomatoes extract two pH optimum were observed, respectively at 6.7 and 8, that probably belong to atleast two isoenzyme, so we named them ISOIPPO for optimum pH at 6.7 and ISOIIPPO for optimum pH at 8.Activity of isoenzymes of PPO in presence of pyrogallol was optimum after incubation at 55°C. Maximum activity of ISOIPPO is 240% and for ISOIIPPO is 157%. Activity increased to 150%, 180%, 200% and 110% after 70 minute incubationat 27, 40, 55 and 70°C for ISOIPPO. This increase in activity for ISOIIPPO is 135%, 157%, 185% and 100% after 70 minute incubation at 27, 40, 55 and 70°C. Activity was constant even after 80 minute incubation at 70°C.Incubation at high temperature (90°C) was accompanied with decrease of activity to 50% and 28% for ISOIPPO and ISOIIPPO, respectively. Keyword:Pyrogallol, Polyphenol oxidase, Solanum lycopersicum, Temperature