PURIFICATION AND BIOCHEMICAL CHARACTERIZATION OF POLYPHENOL OXIDASE FROM AFRICAN EGGPLANT (SOLANUM MACROCARPON) FRUITS

During processing, S. macrocarpon fruits used for culinary and medicinal purposes undergoes browning. PPO (EC 1.14.18.1 or EC 1.10.3.1) Catalyzes the oxidation of phenolic compounds to quinones in the presence of molecular oxygen. These quinones are highly reactive and readily polymerize to form brown, black, or red pigments, a process commonly known as enzymatic browning. In the context of African eggplant, this browning can negatively impact the sensory quality, nutritional value, and marketability of the fruit, particularly after harvesting and during processing. This article describes the PPO extraction, purification and some biochemical characteristics from S. macrocarpon fruits. Aqueous two-phase partitioning which is a non-conventional method was used to purify and concentrate the enzyme and the biochemical characteristics of the partially purified enzymes were identified. Studies on substrate selectivity shows that the enzyme exhibits both diphenolase and monophenolase properties. The preference substrate is catechol, for the partially purified enzyme preparation and the ideal pH and temperature was found to be 6.5 and 50̊C respectively. The Km and Vmax estimates were 1.2 ± 0.2 mM and 68.5 ± 2 min∕mg protein respectively. In conclusion, the biochemical properties exhibited by this enzyme can be useful model for proper understanding of its stability and could be an advantage for industrial processes