Digestive enzyme patterns and evaluation of protease classes in Catla catla (Family: Cyprinidae) during early developmental stages

Digestive enzymes of Catla catla were studied during ontogenic development. Specific amylase activity was 0.12 ± 0.01 mg maltose mg protein− 1 h− 1 in fish 4 days after hatching (DAH) and reached a maximum on (0.41 ± 0.12 mg maltose mg protein− 1 h− 1) 34 DAH. Total protease activity was minimum (123.2 ± 16.5 mU mg protein− 1 min− 1) on day-8 and reached its highest level (2713 ± 147.2 mU mg protein− 1 min− 1) on day-32. Trypsin activity showed constant increasing trend from day-16 onwards and was maximum on day-34 (118.1 ± 7.09 mU mg protein− 1 min− 1). Highest chymotrypsin activity was found on day-32 (1789.0 ± 111.7 mU mg protein− 1 min− 1). Lipase activity was detected in 4 DAH catla. Lipase activity increased steadily from day-22 onwards. SDS-PAGE of crude enzyme extracts showed that high molecular mass bands (41.8-127.8 kDa) appeared during the early stages followed by low molecular mass bands (17.8-37.2 kDa). The number of protease activity bands in substrate SDS-PAGE increased with age of fish. During ontogenesis of carp, soybean trypsin inhibitor (SBTI), PMSF and TLCK inhibited 75.5 ± 1.19% to 92.8 ± 0.85%, 53.3 ± 9.47% to 90.5 ± 2.6% and 39.8 ± 3.8% to 84.7 ± 1.54% of total protease activity, respectively. There was only 2.58 ± 0.66% to 10.21 ± 0.09% inhibition of protease activity with EDTA. SBTI and PMSF inhibited 8 and 4 activity bands, respectively. TLCK, a specific trypsin inhibitor, inhibited four trypsin-like enzymes in carp during ontogenesis.