Stabilisation of trypsin-like enzymes from antarctic krill: Effect of polyols,polysaccharides and proteins

The stabilisation of trypsin-like enzymes purified from krill processing wastewater was studied using different proteins, polyols and polysaccharides. The effect of the different stabilisers was evaluated both in solution and in dry samples of the enzymes. In 40% (w/v) stabiliser solutions, the increase in half-life of enzyme activity followed the pattern: sorbitol > xylitol > glycerol > sucrose > maltodextrins, when polyols and polysaccharides were used. In 3% (w/v) protein solutions, the stabilising effect followed the order: hydrolysed collagen > bovine serum albumin > casein. The best result was obtained in a 50% (w/v) sorbitol solution where a 12-fold half-life increase was achieved. Different mechanisms of stabilisation were observed for these two groups of substances. In 50% (w/w) dry enzyme/stabiliser mixtures, the increase in half-life of krill trypsin-like enzymes was: maltodextrins > sucrose > sorbitol > mannitol > xylitol. Dry samples were also prepared by coprecipitation of the enzyme/stabiliser mixture with 95% ethanol, followed by oven drying of the coprecipitates. Under these conditions, the modified maltodextrin PSM 10 (Reppe-Glykos AB, Sweden) gave the best result with a 25-fold half-life increase. The relevance of this result for the industrial application of krill trypsin-like enzymes is discussed.