Biochemical studies on the characters of polyphenol oxidase from different cultivar of wheat
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Abstract
Polyphenol oxidase (PPO), is well-known to induce browning in wheat-based products. In the present study biochemical study on characteristics of PPO was done and it was observed that PPO from 10 different Pakistani wheat (Triticum aestivum L) cultivars shows higher affinity towards L-DOPA, pH and temperature. It was found that pH 5 shows maximum activity and 30ºC was optimum temperature. At various temperature ranges, study was done. The enzyme was found to be stable at different temperatures up to 70ºC. Among various PPO inhibitors when tested, the most effective inhibitors for the enzyme with 10mM L-DOPA as substrate were EDTA and ascorbic acid. The weakest inhibitors were DDT p-coumeric acid, Ferulic acid, Trans-cinnamic acid, Vanillic acid and Diethyldithiocarbonate. While Cysteine was the least potent inhibitor. Sodium Chloride and Sodium bromide isoproterenol and sodium iodide O-phenanthroline was proved to be effective inhibitors. The effect of SDS on wheat PPOs was studied, and it was studied that PPO activity was increased in presence of 50 mM SDS. The extraction of PPOs activity was increased by adding to the extraction buffer following alcohols methanol acetone, 2-propanol ethanol, and n -butanol. The alcohol n –butanol was found to be most potent alcoholic activator, 2-propanol was next to n-butanol, while the least effect was observed for ethanol and methanol.
Keywords: Triticum aestivum; Polyphenol oxidases(PPOs); Enzyme activation; Detergents; Inhibitors