Low molecular weight serine protease from the viscera of sardinelle (Sardinella aurita) with collagenolytic activity: Purification and characterisation

Effect of feeding habits of fish on the characteristics of collagenolytic proteases isolated from the visceral waste

In this study, influence of feeding habits of fish on the activity of collagenolytic proteases (CP) has been investigated. CP from the visceral waste of freshwater fish (Pangas, Rohu and Common carp) of different feeding habits was isolated and partially purified by 2-steps, (NH₄)₂SO₄ fractionation and dialysis. Enzymatic activity and purification fold was determined in each step. The molecular mass of the enzymes were close to that of serine collagenases. Enzyme was assayed for temperature and pH optima, effect of sodium chloride and inhibitors. Optimum temperature and pH was 40 °C and 7-8 respectively. Soybean trypsin inhibitor inhibited the enzyme activity, whereas, EDTA exerted no effect, led to confirmation of serine collagenases. CP of carnivore was more active over a wide range of temperature and pH compared to herbivore and omnivore. The study revealed that the feeding habit of fish play decides the optimal physiological conditions for maximum activity of CP.

Trypsin from the digestive system of carp Cirrhinus mrigala: purification, characterization and its potential application

Trypsin was purified 35.64-fold with 4.97% recovery from the viscera of carp Cirrhinus mrigala (mrigal) by ammonium sulfate precipitation, ion exchange and affinity chromatography. The purified enzyme was active at a wide range of pH (7.0-9.2) and temperature (10-50°C). The purified enzyme exhibited high thermal stability up to 50°C for 1h. The enzyme activity was stabilized by Ca(+2) (2mM) up to 7h at 40°C. The Km and kcat values of purified enzyme were 0.0672 mM and 92.09/s/mM, respectively. Soybean trypsin inhibitor and phenylmethylsulphonylflouride completely inhibited the enzyme activity. The specific inhibitor of trypsin, N-α-p-tosyl-L-lysine chloromethyl ketone inhibited 99.67% activity. Na(+), K(+) and Li(+) inhibited 20.99 ± 5.25%, 16.53 ± 4.80% and 18.99 ± 1.42% of enzyme activity, respectively. Divalent ions Mg(+2), Zn(+2), Co(+2), Hg(+2) and Cd(+2) inhibited 21.61 ± 2.22%, 31.62 ± 1.78%, 31.62 ± 1.96%, 85.68 ± 1.51% and 47.95 ± 2.13% enzyme activity, respectively. SDS-PAGE showed that the molecular mass of purified enzyme was 21.7 kDa. MALDI-TOF study showed a peptide sequence of AFCGGSLVNENKMHSAGHCYKSRIQV at the N-Terminal. This sequence recorded 76-84% identity with trypsin from Thunnus thynnus and other fish species. This confirmed that the purified protein was trypsin. The purified enzyme has potential applications in detergent and food industry because of its thermal stability and alkaline nature.

Purification, characterization, cDNA cloning and in vitro expression of a serine proteinase from the intestinal tract of sea cucumber (Stichopus japonicus) with collagen degradation activity

Sea cucumber (Stichopus japonicus) autolysis during transportation and processing is a major problem and the specific proteinases responsible for autolysis have not yet been identified. In the present study, a 34 kDa serine proteinase (SP) was isolated to high purity from sea cucumber intestinal tract by a series of column chromatographies. Peptide mass fingerprinting revealed that six peptide fragments were identical to a proprotein convertase subtilisin/kexin type 9 preproprotein from sea cucumber A. japonicus. The enzyme hydrolyzed gelatin effectively at pH 6.0-9.0 and 35-40 °C, and the enzyme activity was strongly inhibited by SP inhibitors. Sea cucumber collagen was hydrolyzed significantly by purified SP at 37 °C and more gradually at 4 °C, suggesting that SP may be involved in autolysis. In addition, the SP gene that codes for 377 amino acid residues was cloned into an E. coli expression vector and expressed in vitro. A polyclonal antibody against rSP was prepared and found to react specifically against both rSP and endogenous SP, which may prove useful for future studies on the physiological functions of SP.

Digestive Alkaline Proteases from Zosterisessor ophiocephalus, Raja clavata, and Scorpaena scrofa: Characteristics and Application in Chitin Extraction

The aim of this work was to study some biochemical characteristics of crude alkaline protease extracts from the viscera of goby (Zosterisessor ophiocephalus), thornback ray (Raja clavata), and scorpionfish (Scorpaena scrofa), and to investigate their applications in the deproteinization of shrimp wastes. At least four caseinolytic proteases bands were observed in zymogram of each enzyme preparation. The optimum pH for enzymatic extracts activities of Z. ophiocephalus, R. clavata, and S. scrofa were 8.0-9.0, 8.0, and 10.0, respectively. Interestingly, all the enzyme preparations were highly stable over a wide range of pH from 6.0 to 11.0. The optimum temperatures for enzyme activity were 50°C for Z. ophiocephalus and R. clavata and 55°C for S. scrofa crude alkaline proteases. Proteolytic enzymes showed high stability towards non-ionic surfactants (5% Tween 20, Tween 80, and Triton X-100). In addition, crude proteases of S. scrofa, R. clavata, and Z. ophiocephalus were found to be highly stable towards oxidizing agents, retaining 100%, 70%, and 66%, respectively, of their initial activity after incubation for 1 h in the presence of 1% sodium perborate. They were, however, highly affected by the anionic surfactant SDS. The crude alkaline proteases were tested for the deproteinization of shrimp waste in the preparation of chitin. All proteases were found to be effective in the deproteinization of shrimp waste. The protein removals after 3 h of hydrolysis at 45°C with an enzyme/substrate ratio (E/S) of 10 were about 76%, 76%, and 80%, for Z. ophiocephalus, R. clavata, and S. scrofa crude proteases, respectively. These results suggest that enzymatic deproteinization of shrimp wastes by fish endogenous alkaline proteases could be applicable to the chitin production process.