Digestive peptidases and proteinases in the midgut gland of the pink shrimp Farfantepenaeus paulensis (Crustacea, Decapoda, Penaeidae)

Author(s)

Buarque, Diego Souza ^{[1, 2]} ; Castro, Patricia Fernandes ^[3] ; Silva Santos, Fabio Marcel ^{[1, 2]} ; Lemos, Daniel ^[4] ; Carvalho Junior, Luiz Bezerra ^{[1, 2]} ; Bezerra, Ranilson Souza ^[2]

Affiliation

^[1] Univ Fed Pernambuco, LIKA, BR-50670420 Recife, PE - Brazil

^[2] Univ Fed Pernambuco, Dept Bioquim, LABENZ, BR-50670420 Recife, PE - Brazil

^[3] Embrapa Meio Norte, Parnaiba, PI - Brazil

^[4] Univ Sao Paulo, Dept Oceanog Biol, Inst Oceanog, Sao Paulo - Brazil

• Document type: Journal article
• Source: AQUACULTURE RESEARCH; v. 40, n. 7, p. 861-870, APR 30 2009.
• Web of Science Citations: 15

Abstract

Proteases from the midgut gland of the Farfantepenaeus paulensis juveniles were assessed. Enzyme activity was determined using protease substrates and inhibitors. The effect of pH, temperature and calcium on proteolytic activity was assayed. Caseinolytic activity was analysed in substrate-sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Trypsin, chymotrypsin and leucine aminopeptidase activity was detected. Proteolytic activity was strongly inhibited by the specific trypsin inhibitors. Tosyl-phenylalanine chloromethyl ketone inhibited 59.3% of chymotrypsin activity. The greatest trypsin-like activity occurred at pH 8.0 and 45 degrees C. Chymotrypsin-like activity reached maximal values at alkaline pH (7.2-9.0) and 55 degrees C. CaCl(2) did not increase trypsin-like activity, but rather inhibited it at concentrations of 30 (20%), 50 (30%) and 100 mM (50%). The substrate-SDS-PAGE zymogram revealed eight proteinase bands. Two possibly thermal-resistant (85 degrees C, 30 min) chymotrypsin isoforms were found, which were inhibited by phenyl-methyl-sulphonyl-fluoride. Aminopeptidase activity of enzyme extracts (Arg, Leu, Lys, Phe and Val) and the recommended concentrations of these essential amino acids in penaeid shrimp diets were positively correlated (P < 0.05). Beause protein digestion involves the combined action of different enzymes, adequate knowledge of shrimp digestion and enzyme characteristics is required for the assessment of the digestive potential of different feed sources and development of in vitro digestibility protocols. (AU)