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

Preparation of micron-sized benzamidine-modified magnetic agarose beads for trypsin purification from fish viscera

The effective method for trypsin purification should be established because trypsin has important economic value. In this work, a novel and simple strategy was proposed for fabricating micron-sized magnetic Fe3O4@agarose-benzamidine beads (MABB) with benzamidine as a ligand, which can efficiently and selectively capture trypsin. The micro-sized MABB, with clear spherical core-shell structure and average particle size of 6.6 μm, showed excellent suspension ability and magnetic responsiveness in aqueous solution. The adsorption capacity and selectivity of MABB towards target trypsin were significantly better than those of non-target lysozyme. According to the Langmuir equation, the maximum adsorption capacity of MABB for trypsin was 1946 mg g-1 at 25 °C, and the adsorption should be a physical sorption process. Furthermore, the initial adsorption rate and half equilibrium time of MABB toward trypsin were 787.4 mg g-1 min-1 and 0.71 min, respectively. To prove the practicability, MABB-based magnetic solid-phase extraction (MSPE) was proposed, and the related parameters were optimized in detail to improve the purification efficiency. With Tris-HCl buffer (50 mM, 10 mM CaCl2, pH 8.0) as extraction buffer, Tris-HCl buffer (50 mM, 100 mM CaCl2, pH 8.0) as rinsing buffer, acidic eluent (0.01 M HCl, 0.5 M NaCl, pH 2.0) as eluent buffer and alkaline buffer (1 M Tris-HCl buffer, pH 10.0) as neutralization solution, the MABB-based MSPE was successfully used for trypsin purification from the viscera of grass carp (Ctenopharyngodon idella). The molecular weight of purified trypsin was determined as approximate 23 kDa through sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The purified trypsin was highly active from 30 °C to 60 °C, with an optimum temperature of 50 °C, and was tolerant to pH variation, exhibiting 85 % of maximum enzyme activity from pH 7.0 to 10.0. The results demonstrated that the proposed MABB-based MSPE could effectively purify trypsin and ensure the biological activity of purified trypsin. Therefore, we believe that the novel MABB could be applicable for efficient purification of trypsin from complex biological systems.

Characterization of digestive enzymes from captive Brazilian flounder Paralichthys orbignyanus

Knowledge of specific enzyme activity, along with animal habits and digestive capacity is essential in formulating an appropriate diet for any species. In this study, we evaluated and characterized the activity of digestive enzymes present in the liver, intestine, and stomach of Paralichthys orbignyanus. The effects of pH and temperature on enzyme activity were also evaluated via the use of specific substrates. The use of specific substrates and inhibitors showed strong evidence of the presence of trypsin (BApNA= 0.51 ± 0.2 mU mg-1), chimotrypsin (SApNA= 2.62 ± 1.8 mU mg-1), and aminopeptidases (Leu-p-Nan =0.9709 ± 0.83 mU mg-1) in the intestine. Optimum pH for the activity of trypsin, chemotrypsin, leucino aminopeptidase, amilase, and pepsin were 9.5, 9.0, 8.0, 7.5, and 3.5, respectively, while optimum temperatures were 50, 50, 50, 40, and 45 °C, respectively. These results provide additional information regarding the biology of Brazilian flounder and can be used as a basis for further studies regarding fish feeding physiology.

Aluminium sulfate exposure: A set of effects on hydrolases from brain, muscle and digestive tract of juvenile Nile tilapia (Oreochromis niloticus)

Aluminium is a major pollutant due to its constant disposal in aquatic environments through anthropogenic activities. The physiological effects of this metal in fish are still scarce in the literature. This study investigated the in vivo and in vitro effects of aluminium sulfate on the activity of enzymes from Nile tilapia (Oreochromis niloticus): brain acetylcholinesterase (AChE), muscle cholinesterases (AChE-like and BChE-like activities), pepsin, trypsin, chymotrypsin and amylase. Fish were in vivo exposed during 14days when the following experimental groups were assayed: control group (CG), exposure to Al₂(SO₄)₃ at 1μg·mL^-1 (G1) and 3μg·mL^-1 (G3) (concentrations compatible with the use of aluminium sulfate as coagulant in water treatment). In vitro exposure was performed using animals of CG treatment. Both in vivo and in vitro exposure increased cholinesterase activity in relation to controls. The highest cholinesterase activity was observed for muscle BChE-like enzyme in G3. In contrast, the digestive enzymes showed decreased activity in both in vivo and in vitro exposures. The highest inhibitory effect was observed for pepsin activity. The inhibition of serine proteases was also quantitatively analyzed in zymograms using pixel optical densitometry as area under the peaks (AUP) and integrated density (ID). These results suggest that the inhibition of digestive enzymes in combination with activation of cholinesterases in O. niloticus is a set of biochemical effects that evidence the presence of aluminium in the aquatic environment. Moreover, these enzymatic alterations may support further studies on physiological changes in this species with implications for its neurological and digestive metabolisms.

Trypsin purification using magnetic particles of azocasein-iron composite

This work presents an inexpensive, simple and fast procedure to purify trypsin based on affinity binding with ferromagnetic particles of azocasein composite (mAzo). Crude extract was obtained from intestines of fish Nile tilapia (Oreochromis niloticus) homogenized in buffer (01g tissue/ml). This extract was exposed to 100mg of mAzo and washed to remove unbound proteins by magnetic field. Trypsin was leached off under high ionic strength (3M NaCl). Preparation was achieved containing specific activity about 60 times higher than that of the crude extract. SDS-PAGE showed that the purified protein had molecular weight (24kDa) in concordance with the literature for the Nile tilapia trypsin. The mAzo composite can be reused and applied to purify trypsin from other sources.

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.

Enzymatic characterizations and activity regulations of N-acetyl-β-D-glucosaminidase from the spermary of Nile tilapia (Oreochromis niloticus)

N-Acetyl-β-D-glucosaminidase (NAGase) is proved to be correlated with reproduction of male animals. In this study, enzymatic characterizations of NAGase from spermary of Nile tilapia (Oreochromis niloticus) were investigated in order to further study its reproductive function in fish. Tilapia NAGase was purified to be PAGE homogeneous by the following techniques: (NH4)2SO4 fractionation (40-55%), DEAE-cellulose (DE-32) ion exchange chromatography, Sephadex G-200 gel filtration and DEAE-Sephadex (A-50). The specific activity of the purified enzyme was 4100 U/mg. The enzyme molecular weight was estimated as 118.0 kD. Kinetic studies showed that the hydrolysis of p-nitrophenyl-N-acetyl-β-D-glucosaminide (pNP-NAG) by the enzyme followed Michaelis-Menten kinetics. The Michaelis-Menten constant (Km) and maximum velocity (Vm) were determined to be 0.67 mM and 23.26 μM/min, respectively. The optimum pH and optimum temperature of the enzyme for hydrolysis of pNP-NAG was to be at pH 5.7 and 55°C, respectively. The enzyme was stable in a pH range from 3.3 to 8.1 at 37°C, and inactive at temperature above 45°C. The enzyme activity was regulated by the following ions in decreasing order: Hg(2+) > Zn(2+) > Cu(2+) > Pb(2+) > Mn(2+). The IC50 of Cu(2+), Zn(2+) and Hg(2+) was 1.23, 0.28, and 0.0027 mM, respectively. However, the ions Li(+), Na(+), K(+), Mg(2+) and Ca(2+) had almost no influence on enzyme activity. In conclusion, the enzymatic characterizations of NAGase from tilapia were special to the other animals, which were correlated with its living habit; besides, CuSO4 and ZnSO4 should used very carefully as insecticides in tilapia cultivation since they both had strong regulations on the enzyme.

Characterisation of thermostable trypsin and determination of trypsin isozymes from intestine of Nile tilapia (Oreochromis niloticus L.)

Trypsin from intestinal extracts of Nile tilapia (Oreochromis niloticus L.) was characterised. Three-step purification - by ammonium sulphate precipitation, Sephadex G-100, and Q Sepharose - was applied to isolate trypsin, and resulted in 3.77% recovery with a 5.34-fold increase in specific activity. At least 6 isoforms of trypsin were found in different ages. Only one major trypsin isozyme was isolated with high purity, as assessed by SDS-PAGE and native-PAGE zymogram, appearing as a single band of approximately 22.39 kDa protein. The purified trypsin was stable, with activity over a wide pH range of 6.0-11.0 and an optimal temperature of approximately 55-60 °C. The relative activity of the purified enzyme was dramatically increased in the presence of commercially used detergents, alkylbenzene sulphonate or alcohol ethoxylate, at 1% (v/v). The observed Michaelis-Menten constant (Km) and catalytic constant (Kcat) of the purified trypsin for BAPNA were 0.16 mM and 23.8 s(-1), respectively. The catalytic efficiency (Kcat/Km) was 238 s(-1) mM(-1).

Characterization of novel β-glucosidases with transglycosylation properties from Trichosporon asahii

Two novel β-glucosidases from Trichosporon asahii, named BG1 and BG2, were purified to electrophoretic homogeneity using ammonium sulfate precipitation, hydrophobic interaction, ion exchange, and gelfiltration chromatography. The molecular weight of BG1 and BG2 were estimated as 160 kDa and 30 kDa, respectively. The K(m), V(max), K(cat), and K(cat)/K(m) values of the two β-glucosidases for p-nitrophenyl-β-D-glucopyranoside were determined. Both enzymes showed relatively high affinity to p-nitrophenyl-β-D-glucopyranoside in 4-nitrophenol glycosides and gentiobiose in saccharide substrates. The enzymes exhibited optimum activity at pH 6.0 and pH 5.5, respectively. Their respective optimum temperatures were 70 and 50 °C. Metal ions and inhibitors had different effects on the enzymes activities. Circular dichroism (CD) spectroscopy demonstrated that the purified BG1 exhibited a β-sheet-rich structure and that BG2 displayed a high random coil conformation. HPLC analysis of transglycosylation and reverse hydrolysis assays revealed that only BG1 possessed transglycosylation activity and synthesized cello-oligosaccharides by the addition of glucose. This suggested that BG1 could be used to produce complex bioactive glycosides and could be considered as a potential enzyme for industrial application.

Solvent-stable digestive alkaline proteinases from striped seabream (Lithognathus mormyrus) viscera: characteristics, application in the deproteinization of shrimp waste, and evaluation in laundry commercial detergents

Alkaline proteases from the viscera of the striped seabream (Lithognathus mormyrus) were extracted and characterized. Interestingly, the crude enzyme was active over a wide range of pH from 6.0 to 11.0, with an optimum pH at the range of 8.0-10.0. In addition, the crude protease was stable over a broad pH range (5.0-12.0). The optimum temperature for enzyme activity was 50 °C. The crude alkaline proteases showed stability towards various surfactants and bleach agents and compatibility with some commercial detergents. It was stable towards several organic solvents and retained more than 50% of its original activity after 30 days of incubation at 30 °C in the presence of 25% (v/v) dimethyl sulfoxide, N,N-dimethylformamide, diethyl ether, and hexane. The crude enzyme extract was also tested for shrimp waste deproteinization in the preparation of chitin. The protein removal with a ratio enzyme/substrate of 10 was about 79%.