Trypsin-like enzyme from intestine and pyloric caeca of spotted goatfish (Pseudupeneus maculatus)

Trypsin-like enzyme was partially purified from the intestine and pyloric caeca of spotted goatfish (Pseudupeneus maculatus) by a simple three steps procedure: heat treatment, ammonium sulphate precipitation and Sephadex G-75 filtration. The enzymes from the intestine and pyloric caeca were 96- and 57.7-fold purified with yield values of 68.1% and 26.1%, respectively. The pyloric caeca enzyme collected from the Sephadex G-75 filtration showed a single band in SDS–PAGE (24.5 kDa). Both enzymes presented identical optima pH (9.0) and temperature (55 °C). After incubation at 45 °C for 30 min, enzymes obtained from intestine remained fully activity while a loss of activity (10%) of enzyme extracted from pyloric caeca was registered. Michaelis constant was not significantly different for trypsin-like enzyme from pyloric caeca (1.82 ± 0.19 mM) and that from the intestine (1.94 ± 0.45 mM) acting on benzoyl-dl-arginine-p-nitroanilide (BAPNA). Finally, their activities were inhibited by the following ions in decreasing order: Al3+ > Zn2+ > Hg2+ = Cu2+ > Cd2+. The effects of Ca2+, Mg2+, Mn2+, Ba2+, K1+, Li1+ and Co2+ showed to be less intensive. The similarities between them provide basis for the proposition of obtaining an attractive protease preparation from the tons of intestine and pyloric caeca, that are usually discarded, from this fish which is an important species exported by North-eastern Brazilian fishery industry.