Aqueous two-phase partitioning of liver proteinase from albacore tuna (Thunnus alalunga): Application to starry triggerfish (Abalistes stellaris) muscle hydrolysis

Abstract

The potential of aqueous two-phase system (ATPS) for the purification and recovery of proteinase from albacore tuna (Thunnus alalunga) liver was explored. Influence of phase compositions such as type of phase forming salts, PEG molecular weight, concentration of salt and PEG, pH of the system, and NaCl addition on partitioning of proteinase was investigated. ATPS comprising PEG1000 (25%, w/w) and NaH2PO4 (20%, w/w) at pH 7.0 provided the best condition for the maximum partitioning of proteinase into the top phase and gave the highest purification factor (5.58-fold) and specific activity (20.65 unit/mg protein). The yield of 89.99% was obtained. The addition of NaCl up to a final concentration of 6% (w/w) decreased the degree of purification and enzyme recovery of proteinase. Based on electrophoresis and activity staining, the fractionated proteinases had the MW 21, 24, 30, and 34 kDa. The effect of fractionated proteinases on starry triggerfish (Abalistes stellaris) muscle hydrolysis was also studied. Fractionated proteinases were able to hydrolyze triggerfish muscle in a dose-dependent manner. Overall, results demonstrated the feasibility of ATPS for the recovery and purification of proteinase without the need for multiple steps, and the obtained proteinase can be further in preparation of protein hydrolysate.