Properties of Pepsin and Trypsin Isolated From the Digestive Tract of Parona Signata ?Palometa?

Two digestive proteases from Parona signata (Palometa) were isolated from gastric and pyloric caeca tissues and characterized. The stomach enzyme was inhibited by pepstatin and was classified as pepsin. Palometa pepsin purified from a Sephadex G-100 column appeared as two bands on an SDS-PAGE gel and exhibited optimum activity at pH 3.5, and 37C. Palometa pepsin was inhibited by pepstatin to a similar exient as porcine pepsin. An enzyme isolated from the pyloric caeca was shown to be trypsin based on its molecular weight, its ability to hydrolyze the synthetic substrates, N-α-benzoyl-arginine-p-nitroanilide (BAPA), and tosyl-arginine methyl ester (TAME) and inhibition by the known trypsin inhibitors, SBTI, TLCK, PMSF and benzamidine. The purified trypsin from palometa pyloric caeca yielded a single band with a molecular mass of 24 kDa. Optima trypsin activity was obtained at pH 8.5 and the enzyme was stable over a pH range of 3 to 11. Palometa trypsin activity was stable for 30 min at 50C, but lost 50% of its activity after 30 min at 60C. The optimum temperature for activity was 65C. The biochemical properties of Palometa trypsin and pepsin were discussed in relation to the varying environment of Palometa in the Rio de la Plata estuary.