Purification and characterization of pectin methylesterase from kiwifruit (Actinidia deliciosa var. Hayward)
2016
Pal, R. S. | Kumar Vandana, A. | Agrawal, S.
Pectin methylesterase (PME; EC 3.1.1.11) is widely distributed in plants. PME involved in de-esterification of pectin and have applicability in food, textiles, wines, pulp, and paper industries. In the present study, PME was purified from ripe kiwi fruit (cv. Hayward) using conventional techniques of ammonium sulphate fractionation (30-80% saturation), gel fitration through Sephadex G-75 column chromatography and ion exchange chromatography on DEAE-shephadex. After ammonium sulphate precipitation and dialysis, specific activity of the enzyme was found to be 6.34 units mg-1 protein and after chromatoghraphy techniques the specific activity of the enzyme was found to be 64.11 units mg-1 protein. Enzyme was purified about 20.75 fold and 37.90 recovery. During optimization of enzyme extraction, the enzyme showed maximum activity at pH 7.5. Stability was found at pH range 7-8, with optimum temperature 30°C. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) yielded a single major band with molecular weight of 45 kDa indiacting that enzyme was a monomer. The enzyme showed a typical hyperbolic response with increasing concentrations of substrate revealing that it followed Michaelis-Menten kinetics. From the double reciprocal plot, Km value for the PME was found, that is 0.164 mg ml-1. The results obtained in the present study would indicate that Km value of kiwifruit PME was found comparatively lower then other sources. This indicates that ripen kiwifruit PME had higher affinity for the substrate then others.
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