Thermodynamic activation and structural analysis of trypsin I from Monterey sardine (Sardinops sagax caerulea)

Characterization and Hydrolysis Mechanism Analysis of a Cold-Adapted Trypsin-Like Protease from Antarctic Krill

Cold-adapted proteases are capable of efficient protein hydrolysis at reduced temperatures, which offer significant potential applications in the area of low temperature food processing. In this paper, we attempted to characterize cold-adapted proteases from Antarctic krill. Antarctic krill possesses an extremely active autolytic enzyme system in their bodies, and the production of peptides and free amino acids accompanies the rapid breakdown of muscle proteins following the death. The crucial role of trypsin in this process is recognized. A cold-adapted trypsin named OUC-Pp-20 from Antarctic krill genome was cloned and expressed in Pichia pastoris. Recombinant trypsin is a monomeric protein of 26.8 ± 1.0 kDa with optimum reaction temperature at 25 °C. In addition, the catalytic specificity of OUC-Pp-20 was assessed by identifying its hydrolysis sites through LC-MS/MS. OUC-Pp-20 appeared to prefer Gln and Asn at the P1 position, which is an amino acid with an amide group in its side chain. Hydrolysis reactions on milk and shrimp meat revealed that it can effectively degrade allergenic components in milk and arginine kinase in shrimp meat. These findings update the current knowledge of cold-adapted trypsin and demonstrate the potential application of OUC-Pp-20 in low temperature food processing.

Sustainable Upcycling of Fisheries and Aquaculture Wastes Using Fish-Derived Cold-Adapted Proteases

The fisheries and aquaculture industries are some of the major economic sectors in the world. However, these industries generate significant amounts of wastes that need to be properly managed to avoid serious health and environmental issues. Recent advances in marine waste valorization indicate that fish waste biomass represents an abundant source of high-value biomolecules including enzymes, functional proteins, bioactive peptides, and omega-3 rich oils. Enzyme-assisted processes, for the recovery of these value-added biomolecules, have gained interest over chemical-based processes due to their cost-effectiveness as well as their green and eco-friendly aspects. Currently, the majority of commercially available proteases that are used to recover value-added compounds from fisheries and aquaculture wastes are mesophilic and/or thermophilic that require significant energy input and can lead to unfavorable reactions (i.e., oxidation). Cold-adapted proteases extracted from cold-water fish species, on the other hand, are active at low temperatures but unstable at higher temperatures which makes them interesting from both environmental and economic points of view by upcycling fish waste as well as by offering substantial energy savings. This review provides a general overview of cold-adapted proteolytic enzymes from cold-water fish species and highlights the opportunities they offer in the valorization of fisheries and aquaculture wastes.

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.

Refolding and Activation from Bacterial Inclusion Bodies of Trypsin I from Sardine (Sardinops sagax caerulea)

BACKGROUND

Trypsin from fish species is considered as a cold-adapted enzyme that may find potential biotechnological applications. In this work, the recombinant expression, refolding and activation of Trypsin I (TryI) from Monterey sardine (Sardinops sagax caerulea) are reported.

METHODS

TryI was overexpressed in Escherichia coli BL21 as a fusion protein of trypsinogen with thioredoxin. Refolding of trypsinogen I was achieved by dialysis of bacterial inclusion bodies with a recovery of 16.32 mg per liter of Luria broth medium.

RESULTS

Before activation, the trypsinogen fusion protein did not show trypsin activity. Trypsinogen I was activated by adding 0.002 U of native TryI purified from the sardine pyloric caeca (nonrecombinant). The activated recombinant trypsin showed three times more activity than the nonrecombinant trypsin alone.

CONCLUSION

The described protocol allowed obtaining sufficient amounts of recombinant TryI from Monterey sardine fish for further biochemical and biophysical characterization of its coldadaptation parameters.

Gene analysis and structure prediction for the cold-adaption mechanism of trypsin from the krill Euphausia superba (Dana, 1852)

BACKGROUND

The ability of Antarctic krill, Euphausia superba (Dana, 1852), to thrive in a cold environment comes from its capacity to synthesize cold-adapted enzymes. Its trypsin, as a main substance in the metabolic reactions, plays a key role in the adaption to low temperatures. However, the progress of research on its cold-adaption mechanism is being influenced due to the limited information on its gene and spatial structure.

RESULTS

We studied the gene of E. superba trypsin with transcriptome sequencing first, and then discussed its cold-adaption mechanism with the full gene and predicted structure basing on bioinformatics. The results showed the proportion of certain residues played important roles in the cold-adaptation behavior for trypsin. Furthermore, a higher proportion of random coils and reduced steric hindrance might also be key factors promoting its cold adaption.

CONCLUSION

This research aimed to reveal the cold-adaption mechanism of E. superba trypsin and provide support for basic research on molecular modification by site-directed mutagenesis of complementary DNA used to produce new and improved recombinant variants with cold adaption. Furthermore, it may broaden its commercial application on minimizing undesirable changes elevated at higher temperature in food processing and in treatment of trauma and inflammation in medicine. © 2017 Society of Chemical Industry.

Investigation on potential enzyme toxicity of clenbuterol to trypsin

Clenbuterol (CLB) is a kind of β2-adrenergic agonists which was illegally used as feed additives nowadays. The toxic interaction of CLB with trypsin, an important digestive enzyme, was studied in vitro using multi-spectroscopic methods and molecular modeling methods. CLB was proved to bind with trypsin in S1 pocket, forming a complex driven by the dominant force of H-bond. The binding constant was calculated to be 1.79887×10(5) L mol(-1) at 289 K and 0.32584×10(5) L mol(-1) at 310 K, respectively. The skeleton of trypsin became loosened and unfolded with the amino residues microenvironment changed. The secondary and tertiary structure of trypsin also varied. Molecular modeling studies illustrated specific display of the binding information and explained most of the experiment phenomena. The binding site of CLB induced the fluorescence quenching as well as inhibition of enzyme activity of trypsin. The study confirmed that CLB had potential toxicity on both the structure and function of trypsin and the effects enhanced with the increasing concentration of CLB.