Isolation, Partial Purification and Characterization of Polyphenol Oxidase (PPO) from Musa Paradisiaca

Polyphenol oxidase or tyrosinase which is universally present in plants, animals, fungi and bacteria, catalyses two different oxidative reactions combining with molecular oxygen. It causes the hydroxylation of monophenols into odiphenols and further oxidation of o-diphenols into o-quinones. Subsequent polymerisation of o-quinones results in the discoloration of tissues and loss of nutrients from fruits and vegetables. In the present study, PPO (E.C number 1.14.18.1) was extracted from banana (Musa paradisiaca) and partially purified by acetone precipitation. The enzyme was found to have high affinity towards its substrate, catechol and the Michaelis Menten constant was observed as 1mM. The optimum pH and temperature of the enzyme were determined to be 5.0 and 50°C respectively. In this study, various plant extracts like Glycyrrhiza glabra, Rubia cordifolia, Hesperethusa crenulata and oil from the seeds of Hydnocarpus laurifolia and purified compounds like Curcumin, Psoralenwere observed to modulate the activity of PPO. These compounds can be used in skin care cosmetics and in the treatment of skin diseases like vitiligo, leucoderma etc.