Purification and characteristics of trypsin from masu salmon (Oncorhynchus masou) cultured in fresh-water

An innovative insecticidal approach based on plant protease inhibitor and Bt protoxins inhibits trypsin-like activity in zebrafish

The Leucaena leucocephala trypsin inhibitor (LTI) + Bacillus thuringiensis (Bt) protoxins mix has been proposed as a novel larvicide agent in order to control the vector mosquito of dengue virus, Aedes aegypti, in their aquatic breeding sites. However, use of this insecticide formulation has raised concerns about its impacts on aquatic biota. In this context, this work aimed to assess the effects of LTI and Bt protoxins, separately or in combination, in zebrafish, in regard to the evaluation of toxicity at early life stages and to the presence of LTI inhibitory effects on intestinal proteases of this fish. Results showed that LTI and Bt concentrations (250 mg/L, and 0.13 mg/L, respectively), and LTI + Bt mix (250 mg/L + 0.13 mg/L) - 10 times superior to those with insecticidal action - did not cause death nor did it induce morphological changes during embryonic and larval development (3 to 144 h post-fertilization) of zebrafish. Molecular docking analyses highlighted a possible interaction between LTI and zebrafish trypsin, especially through hydrophobic interactions. In concentrations near to those with larvicidal action, LTI (0.1 mg/mL) was able to inhibit in vitro intestinal extracts of trypsin in female and male fish by 83 % and 85 %, respectively, while LTI + Bt mix promoted trypsin inhibition of 69 % in female and 65 % in male ones. These data show that the larvicidal mix can potentially promote deleterious effects to nutrition and survival in non-target aquatic organisms, especially those with trypsin-like dependent protein digestion.

Protein hydrolysates derived from aquaculture and marine byproducts through autolytic hydrolysis

Autolysis technology has shown potential for protein hydrolysates production from marine and aquaculture byproducts. Viscera are a source of cheap proteolytic enzymes for producing protein hydrolysates from the whole fish or processing byproducts of the most valuable commercial species by applying autolysis technology. The use of autolysis allows economical production of protein hydrolysate and provides an opportunity to valorize downstream fish and shellfish processing byproducts at a lower cost. As a result, production and application of marine byproduct autolysates is increasing in the global protein hydrolysates market. Nevertheless, several restrictions occur with autolysis, including lipid and protein oxidation mediated by the heterogeneous composition of byproducts. The generally poor storage and handling of byproducts may increase the formation of undesirable metabolites during autolysis, which can be harmful. The formation of nitrogenous compounds (i.e., biogenic amines), loss of freshness, and process of autolysis in the byproducts could increase the rate of quality and safety loss and lead to more significant concern about the use of autolysates for human food applications. The current review focuses on the autolysis process, which is applied for the hydrolysis of aquaculture and marine discards to obtain peptides as functional or nutritive ingredients. It further addresses the latest findings on the mechanisms and factors contributing the deterioration of byproducts and possible ways to control oxidation and other food quality and safety issues in raw materials and protein hydrolysates.

A thermostable trypsin from freshwater fish Japanese dace (Tribolodon hakonensis): a comparison of the primary structures among fish trypsins

Trypsin from Japanese dace (Tribolodon hakonensis) (JD-T) living in freshwater (2-18 °C) was purified. JD-T represented typical fish trypsin characteristics regarding the effects of protease inhibitor, calcium-ion, and pH. For the effect of temperature, JD-T quite resembled to the trypsins from tropical-zone marine fish and freshwater fish (the catfish cultured in Thailand), i.e., the optimum temperature was 60 °C, and it was stable below 60 °C at pH 8.0 for 15 min incubation. From the data, it seemed that the trypsin from freshwater fish is thermostable in spite of the fact that their habitat temperatures are low. So, we determined the primary structure of JD-T to discuss its thermostability-structure relationship. JD-T possessed basic structural features of fish trypsin such as the catalytic triad, the Asp189 residue for substrate specificity, 12 Cys residues forming six disulfide-bridges, and the calcium-ion-binding loop. On the other hand, the contents of charged amino acid residues in whole JD-T molecule (16.2%) and N-terminal region (13.8%) were similar to those of tropical-zone marine fish and other freshwater fish trypsins. Then, JD-T conserved the five amino acid residues (Glu70, Asn72, Val75, Glu77, and Glu80) coordinate with calcium-ion, and the proportion of negatively charged amino acids to charged amino acids in the calcium-ion-binding region of JD-T (75.0%) was equivalent to those of tropical-zone marine fish and freshwater fish trypsins. Therefore, it was suggested that the high thermostability of JD-T are stemmed from these structural specificities.

Characterization and ontogenetic development of digestive enzymes in Pacific bluefin tuna Thunnus orientalis larvae

The major digestive enzymes in Pacific bluefin tuna Thunnus orientalis larvae were characterized, and the physiological characteristics of the enzymes during early ontogeny were clarified using biochemical and molecular approaches. The maximum activity of trypsin (Try), chymotrypsin (Ct) and amylase (Amy) was observed at pH 6-11, 8-11 and 6-9, respectively. Maximum activity of Try, Ct and Amy occurred at 50 °C, that of lipase (Lip) was at 60 °C and that of pepsin (Pep) was at 40-50 °C. These pH and thermal profiles were similar to those for other fish species but differed from those previously reported for adult bluefin tuna. Enzyme activity for all enzymes assayed was found to decrease at high temperatures (Try, Ct, Amy and Pep: 50 °C; Lip: 40 °C), which is similar to findings for other fish species with one marked exception-increased Try activity was observed at 40 °C. Lip activity appeared to be dependent on bile salts under our assay conditions, resulting in a significant increase in activity in the presence of bile salts. Ontogenetic changes in pancreatic digestive enzymes showed similar gene expression patterns to those of other fish species, whereas marked temporal increases in enzyme activities were observed at 10-12 days post hatching (dph), coinciding with previously reported timing of the development of the pyloric caeca in bluefin tuna larvae. However, complete development of digestive function was indicated by the high pep gene expression from 19 dph, which contradicts the profile of Pep activity and previously reported development timing of the gastric gland. These findings contribute to the general knowledge of bluefin tuna larval digestive system development.

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.

Characterisation of trypsin purified from the viscera of Tunisian barbel (Barbus callensis) and its application for recovery of carotenoproteins from shrimp wastes

Trypsin was purified from the viscera of barbel by precipitation using ammonium sulphate (0-80%), Sephadex G-100, and Mono Q-Sepharose ion exchange chromatography. The trypsin was purified 27-fold, with 79U/mg specific activity and 31% recovery. The enzyme had a molecular weight of 24kDa; purified trypsin appeared as a single band on native-PAGE. The optimum pH and temperature for enzyme activity were pH 10.0 and 55°C with BAPNA used as a substrate. The N-terminal amino acid sequence of the first 12 amino acids of the purified trypsin was IVGGYECTPYSQ. The Michaelis-Menten constant (K_m) and catalytic constant (k_cat) values of the enzyme were 0.018mM and 1.21s^-1, respectively. The study also investigated the effects of purified trypsin on the recovery of carotenoproteins from shrimp (Parapenaeus longirostris) shells through hydrolysis using 1.0U barbel trypsin/g shrimp shells for 1h at 30°C. The freeze-dried carotenoproteins recovered contained 71.09% protein, 16.47% lipid, 7.78% ash, and 1.79% chitin.

Mackerel trypsin purified from defatted viscera by supercritical carbon dioxide

Viscera of mackerel (Scomber sp.) were defatted by supercritical carbon dioxide (SCO(2)) treatment. Trypsin (SC-T) was then extracted from the defatted powder and purified by a series of chromatographies including Sephacryl S-200 and Sephadex G-50. The purified SC-T was nearly homogeneous on SDS-PAGE, and its molecular weight was estimated as approximately 24,000 Da. N-terminal twenty amino acids sequence of SC-T was IVGGYECTAHSQPHQVSLNS. The specific trypsin inhibitors, soybean trypsin inhibitor and TLCK, strongly inhibited the activities of SC-T. The pH and temperature optimums of SC-T were at around pH 8.0 and 60°C, respectively, using N(α)-p-tosyl-L-arginine methyl ester as a substrate. The SC-T was unstable below pH 5.0 and above 40°C, and it was stabilized by calcium ion. These enzymatic characteristics of SC-T were the same as those of other fish trypsins, especially spotted mackerel (S. borealis) trypsin, purified from viscera defatted by acetone. Therefore, we concluded that the SCO(2) defatting process is useful as a substitute for organic solvent defatting process.

Purification and characterization of trypsin from the intestine of hybrid tilapia (Oreochromis niloticusxO.aureus)

Trypsin from the intestine of hybrid tilapia (Oreochromis niloticus x O.aureus) was purified by the following techniques: acetone precipitation, ammonium sulfate fractionation, Sephacryl S-200 gel filtration, and DEAE-sephacel ion exchange chromatography. The purified enzyme was determined to be homogeneous by polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate (SDS)-PAGE. The molecular weight was estimated as 22,000 Da. The optimum pH and temperature of the enzyme for the hydrolysis of casein were determined to be 9.0 and 60 degrees C, respectively. The enzyme was stable over a broad pH range from 7.0 to 12.0 at 30 degrees C, and the enzyme was inactive at temperatures above 50 degrees C. The behavior of the enzyme for the hydrolysis of casein followed Michaelis-Menten kinetics with Km of 0.46 mg/mL. The purified enzyme was inhibited by the general serine protease inhibitor phenyl methyl sulphonyl fluoride (PMSF) and also by the specific trypsin inhibitor N-p-tosyl-L-lysine chloromethyl ketone (TLCK) using Nalpha-CBZ-L-lysine p-nitrophenyl ester hydrochloride (CBZ-Lys.pNP) as a substrate. The protease was inhibited by the following ions in decreasing order: Zn2+>Fe3+>Cu2+>Al3+>Co2+=Pb2+>Cd2+>Mn2+. The ions Li+, Na+, K+, Mg2+, and Ba2+ had little effect on the enzyme, and Ca2+ can partially promote its activity at low concentration.