EXTRACTION OF CYSTATIN (ENZYME INHIBITORS) FROM ANIMAL SLAUGHTERHOUSE WASTES

Abstract

The ammonium sulphate precipitation method was used for the extraction of cystatin from bovine lungs, pancreas and a mixture of lungs and pancreas. The main aim of this study was to determine the highest cystatin yield from each of the samples and make recommendations to the industry as to whether a separation of these animal wastes are needed during the slaughtering and rendering processes. The effects of incubation time (15, 30, 45, 60 mins), pH (6.5, 7.0, 7.5, 8.0) and ammonium sulphate saturations (25-45% and 45-65%) on total protein (TP), total activity (TA), specific activity (SA) and yield (Y) were studied. The optimum conditions for total activity (TA), specific activity (SA) and yield (Y) of cystatin during ammonium sulphate extraction were an incubation time of 30 min, a pH of 7.5 and an ammonium sulphate saturation of 45-65%. Among the three samples, the lung produced the high yield of 60.07% at optimum conditions. Under these optimum conditions, the bovine pancreas and the mixture of lung and pancreas produced 39.57% and 51.89%, respectively. The effects of pH and temperature on the maximal inhibitory activity of cystatin obtained from the three samples were evaluated. The optimal pH and temperature for all the three samples were 7.5 and 50 ºC, respectively. The bovine lung sample exhibited a maximal inhibitory activity of 56.8 % at the optimal pH of 7.5 and temperature of 50ºC. Under the same conditions of pH and temperature, the bovine pancreas and the mixture of lung and pancreas samples showed an inhibitory activity of 25.8% and 43.8%, respectively. The bovine lung sample produced the highest values of TP, TA, SA, and Y of cystatin. During the slaughtering process, the lung should be separated from the pancreas in order to recover better cystatin yield.