Biochemical characterization of trypsin from Indonesian skipjack tuna (Katsuwonus pelamis) viscera

Trypsin production from skipjack tuna (Katsuwonus pelamis) viscera is one significant way to increase the value of fish's industrial waste. The present work reports the biochemical properties of trypsin from skipjack tuna viscera. The trypsin was fractionated using 0-60% ammonium sulfate and dialyzed. The enzyme was characterized to find the optimum temperature and pH for the substrate N-alpha-benzoyl-dl-arginine-p-nitroanilide. The 40-50% ammonium sulfate fractionation showed the highest activity at a specific activity of 1.66 U/mg and yield of 69.91%. Specific activity increased after dialysis to 2.17 U/mg with 4.49 times purity and yield of 39.20%. The molecular weights of the enzymes were estimated as 25, 29, and 35 kDa based on the enzyme activity separated by electrophoresis. The enzyme worked optimally at a temperature and pH of 50-60 degrees C and 8.0, respectively. Metal ions (Ca2+, K+, Na+, Mg2+) at a concentration of 20 mM showed no influence on the activity. Enzyme activity was inhibited by Zn2+ at 20 mM, phenyl methyl sulfonyl fluoride (PMSF), benzamidine, and soybean trypsin inhibitor (SBTI), which confirmed the characteristics of a serine protease.