Kinetic characteristics of partially purified invertase from Citrullus lanatus Rind

Invertases are enzymes that hydrolyze sucrose to produce equimolar mixture of glucose and fructose. They are widely used in various industrial food applications. The aim of this study was to isolate, partially purify, and characterize invertase from Citrullus lanatus rind. Invertase isolated from C. lanatus rind was purified to 46.94 folds with 23.19% yield by means of ammonium sulphate precipitation, dialysis and Sephadex G-25 gel filtration chromatography.

The enzyme has an optimum temperature of 50 °C and maximum activity at pH 7 and a relatively high activity at pH 4. Invertase enzyme from C. lanatus rind maintained its activity at 50 °C and 95 °C after 20 minutes of incubation. Maximum activity of the enzyme occurred at 0.25 M sucrose concentration. Kinetic parameters, Vmax and Km were 15 mM and 40 μM/min, respectively. C. lanatus rind invertase was competitively inhibited by Fe²⁺, Cu²⁺, Mg²⁺ and Ag²⁺, while Co²⁺ enhanced its activity. Zn²⁺ has relatively little or no effect on the activity. Thus, C. lanatus rind may be employed as a local source for the production of invertase enzyme.