Two trypsin isoforms from albacore tuna (Thunnus alalunga) liver: Purification and physicochemical and biochemical characterization

Development of an effective method for purifying trypsin using a recombinant inhibitor

A trypsin affinity material was prepared by covalently immobilizing buckwheat trypsin inhibitor (BTI) on epichlorohydrin-activated cross-linked agarose gel (Selfinose CL 6 B). The optimal conditions for activating Selfinose CL 6 B were 15 % epichlorohydrin and 0.8 M NaOH at 40 °C for 2 h. The optimal pH for immobilizing BTI was 9.5. BTI-Sefinose CL 6 B showed a maximum adsorption capacity of 2.25 mg trypsin/(g support). The material also displayed good reusability, retaining over 90 % of its initial adsorption capacity after 30 cycles. High-purity trypsin was obtained from locust homogenate using BTI-Selfinose CL 6 B through one-step affinity chromatography. The molecular mass and Km value of locust trypsin were determined as 27 kDa and 0.241 mM using N-benzoyl-DL-arginine-nitroanilide as substrate. The optimal temperature and pH of trypsin activity were 55 °C and 9.0, respectively. The enzyme exhibited good stability in the temperature range of 30-50 °C and pH range of 4.0-10.0. BTI-Selfinose CL 6 B demonstrates potential application in the preparation of high-purity trypsin and the discovery of more novel trypsin from various species.

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.

Trypsin from Pyloric Caeca of Asian Seabass: Purification, Characterization, and Its Use in the Hydrolysis of Acid-Soluble Collagen

The study aimed to purify trypsin from the pyloric caeca of Asian seabass (Lates calcarifer), and investigate its proteolytic capability toward acid-soluble collagen (ASC) in comparison with commercial porcine trypsin (CPT). Trypsin was purified from pyloric caeca, a leftover from the evisceration process, via ammonium sulphate (40-60% saturation) precipitation, and a soybean trypsin inhibitor (SBTI)-Sepharose 4B column. A 18.5-fold purification and a yield of 15.2% were obtained. SDS-PAGE analysis confirmed a single band of trypsin with a molecular weight of 23.5 kDa. Purified trypsin also showed the single band in native-PAGE. The optimal pH and temperature of trypsin for BAPNA (the specific substrate for amidase) hydrolysis were 8.5 and 60 °C, respectively. The trypsin was stable within the pH range of 7.0-9.5 and temperature range of 25-55 °C. Protease inhibition study confirmed that the purified enzyme was trypsin. The purified trypsin had a Michaelis-Menten constant (Km) and catalytic constant (kcat) of 0.078 mM and 5.4 s-1, respectively, when BAPNA was used. For the hydrolysis of TAME (the specific substrate for esterase), the Km and Kcat were 0.09 mM and 4.8 s-1, respectively. Partially purified seabass trypsin (PPST) had a slightly lower hydrolysis capacity toward ASC than CPT, as evidenced by the lower degree of hydrolysis and protein degradation when the former was used. Both the α-chain and β-chain became more degraded as the hydrolysis time increased. Based on MALDI-TOP, peptides with MW of 2992-2970 Da were dominant in the hydrolysates. Therefore, seabass trypsin could be used in the production of hydrolyzed collagen. It could have economic importance to the market, by replacing some commercial proteases, which have religious constraints.

Biomass-derived magnetic nanocomposites modified by choline chloride/citric acid based natural deep eutectic solvents for the magnetic solid phase extraction of trypsin

A novel biomass-derived magnetic nanocomposite of Fe₃O₄-Chitin@NADES-CC composed of a natural deep eutectic solvent (NADES), biological polysaccharide (Chitin) and magnetic Fe₃O₄ was synthesized. After being systematically characterized by Fourier transform infrared spectrometry, thermogravimetry, vibrating sample magnetometry, X-ray diffraction, transmission electron microscopy and dynamic light scattering, Fe₃O₄-Chitin@NADES-CC was used as an extractant to separate trypsin (Tryp) on the basis of magnetic solid phase extraction. Simultaneously, the extraction conditions of Fe₃O₄-Chitin@NADES-CC for Tryp were investigated in turn by single-factor experiments, including screening the types of extractants, the initial concentration of Tryp, the pH value of the solution, the influence of ionic strength, extraction time and temperature, etc. Under the optimal conditions, the extraction capacity of Fe₃O₄-Chitin@NADES-CC for Tryp could reach up to 1082.67 mg g^-1. Adsorption isotherm tests certified that the Langmuir adsorption equilibrium fitted well with the extraction model in this study, which showed that the extraction of Fe₃O₄-Chitin@NADES-CC for Tryp was monolayer adsorption. In addition, in the sections on the regeneration-reuse, selectivity and methodological studies, all the results exhibited the superiority of the Fe₃O₄-Chitin@NADES-CC and Tryp separation strategy which has been established in this work. Finally, Fe₃O₄-Chitin@NADES-CC was ultimately applied to the separation of Tryp from a real bovine pancreas crude extract by the analysis of SDS-PAGE. All the above results highlight that the proposed Fe₃O₄-Chitin@NADES-CC biomass-derived magnetic nanocomposite can be applied in the field of protein purification.

Physicochemical and Biochemical Properties of Trypsin-like Enzyme from Two Sturgeon Species

This work aimed to determine the physicochemical and biochemical properties of trypsin from beluga Huso huso and sevruga Acipenser stellatus, two highly valuable sturgeon species. According to the results obtained from the methods of casein-zymogram and inhibitory activity staining, the molecular weight of trypsin for sevruga and beluga was 27.5 and 29.5 kDa, respectively. Optimum pH and temperature values for both trypsins were recorded at 8.5 and 55 °C by BAPNA (a specific substrate), respectively. The stability of both trypsins was well-preserved at pH values from 6.0 to 11.0 and temperatures up to 50 °C. TLCK and SBTI, two specific trypsin inhibitors, showed a significant inhibitory effect on the enzymatic activity of both trypsins (p < 0.05). The enzyme activity was significantly increased in the presence of Ca⁺² and surfactants and decreased by oxidizing agents, Cu⁺², Zn⁺², and Co⁺² (p < 0.05). However, univalent ions Na⁺ and K⁺ did not show any significant effect on the activity of both trypsins (p > 0.05). The results of our study show that the properties of trypsin from beluga and sevruga are in agreement with data reported in bony fish and can contribute to the clear understanding of trypsin activity in these primitive species.

Characterization of the trypsin-III from Monterey sardine (Sardinops caeruleus): Insights on the cold-adaptation from the A236N mutant

Trypsins (E.C. 3.4.21.4) are digestive enzymes that catalyze the hydrolysis of peptide bonds containing arginine and lysine residues. Some trypsins from fish species are active at temperatures just above freezing, and for that are called cold-adapted enzymes, having many biotechnological applications. In this work, we characterized a recombinant trypsin-III from Monterey sardine (Sardinops caeruleus) and studied the role of a single residue on its cold-adapted features. The A236N mutant from sardine trypsin-III showed higher activation energy for the enzyme-catalyzed reaction, it was more active at higher temperatures, and exhibited a higher thermal stability than the wild-type enzyme, suggesting a key role of this residue. The thermodynamic activation parameters revealed an increase in the activation enthalpy for the A236N mutant, suggesting the existence of more intramolecular contacts during the activation step. Molecular models for both enzymes suggest that a hydrogen-bond involving N236 may contact the C-terminal α-helix to the vicinity of the active site, thus affecting the biochemical and thermodynamic properties of the enzyme.

Effects of temperature on feeding and digestive processes in fish

As most fish are ectotherms, their physiology is strongly affected by temperature. Temperature affects their metabolic rate and thus their energy balance and behavior, including locomotor and feeding behavior. Temperature influences the ability/desire of the fish to obtain food, and how they process food through digestion, absorb nutrients within the gastrointestinal tract, and store excess energy. As fish display a large variability in habitats, feeding habits, and anatomical and physiological features, the effects of temperature are complex and species-specific. The effects of temperature depend on the timing, intensity, and duration of exposure as well as the speed at which temperature changes occur. Whereas acute short-term variations of temperature might have drastic, often detrimental, effects on fish physiology, long-term gradual variations might lead to acclimation, e.g. variations in metabolic and digestive enzyme profiles. The goal of this review is to summarize our current knowledge on the effects of temperature on energy homeostasis, with specific focus on metabolism, feeding, digestion, and how fish are often able to "adapt" to changing environments through phenotypic and physiological changes.

Differences in Gene Expression Profiles of Seven Target Proteins in Third-Stage Larvae of Anisakis simplex (Sensu Stricto) by Sites of Infection in Blue Whiting (Micromesistius poutassou)

The third-stage larvae of the parasitic nematode genus Anisakis tend to encapsulate in different tissues including the musculature of fish. Host tissue penetration and degradation involve both mechanic processes and the production of proteins encoded by an array of genes. Investigating larval gene profiles during the fish infection has relevance in understanding biological traits in the parasite’s adaptive ability to cope with the fish hosts’ defense responses. The present study aimed to investigate the gene expression levels of some proteins in L3 of A. simplex (s.s.) infecting different tissues of blue whiting Micromesistius poutassou, a common fish host of the parasite in the NE Atlantic. The following genes encoding for Anisakis spp. proteins were studied: Kunitz-type trypsin inhibitor (TI), hemoglobin (hb), glycoprotein (GP), trehalase (treh), zinc metallopeptidase 13 (nas 13), ubiquitin-protein ligase (hyd) and sideroflexin 2 (sfxn 2). Significant differences in gene transcripts (by quantitative real-time PCR, qPCR) were observed in larvae located in various tissues of the fish host, with respect to the control. ANOVA analysis showed that relative gene expression levels of the seven target genes in the larvae are linked to the infection site in the fish host. Genes encoding some of the target proteins seem to be involved in the host tissue migration and survival of the parasite in the hostile target tissues of the fish host.

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.