Actinidin: A Promising Milk Coagulating Enzyme

The aim of this work was to study proteolytic activity of actinidin in comparison with chymosin and ficin on bovine milk substrate. The specific activities of purified ficin and actinidin were 7.9 and 8.3 unit/mg protein, respectively. The optimum clotting activity of both actinidin and ficin was at 45°C, although chymosin was relatively less sensitive to temperature. Increasing CaCl2 concentration resulted in an enhancement of the clotting activities of all coagulating enzymes, this effect noticeable for ficin. In ficin treated sample significant decrease of bands intensity in the range 25-30 KD and appearance of some of κ-casein in 20 KD regions was observed by using SDS-PAGE. In conclusion, the chymosin and actinidin gave similar relative activity at different temperatures, pH values and CaCl2 concentrations for bovine milk substrate. Comparable electrophoresis profile of actinidin, ficin and chymosin by analysis of the whey with SDS-PAGE indicates that actinidin could be a potential alternative for chymosin.