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In recent years, the extraction of hypoglycemic peptides from food proteins has gained increasing attention. Neuropeptides, hormone peptides, antimicrobial peptides, immune peptides, antioxidant peptides, hypoglycemic peptides and antihypertensive peptides have become research hotspots. In this study, bioinformatic methods were used to screen and predict the properties of pig collagen-derived hypoglycemic peptides, and their inhibitory effects on α-glucosidase were determined in vitro. Two peptides (RL and NWYR) were found to exhibit good water solubility, adequate ADMET (absorption, distribution, metabolism, elimination, and toxicity) properties, potentially high biological activity, and non-toxic. After synthesizing these peptides, NWYR showed the best inhibitory effect on α-glucosidase with IC50 = 0.200±0.040 mg/mL, and it can regulate a variety of biological processes, play a variety of molecular functions in different cellular components, and play a hypoglycemic role by participating in diabetic cardiomyopathy and IL-17 signaling pathway. Molecular docking results showed that NWYR had the best binding effect with the core target DPP4 (4n8d), with binding energy of -8.8 kcal/mol. NWYR mainly bonded with the target protein through hydrogen bonding, and bound with various amino acid residues such as Asp-729, Gln-731, Leu-765, etc., thus affecting the role of the target in each pathway. It is the best core target for adjuvant treatment of T2DM. In short, NWYR has the potential to reduce type 2 diabetes, providing a basis for further research or food applications as well as improved utilization of pig by-products. However, in subsequent studies, it is necessary to further verify the hypoglycemic ability of porcine collagen active peptide (NWYR), and explore the hypoglycemic mechanism of NWYR from multiple perspectives such as key target genes, protein expression levels and differences in metabolites in animal models of hyperglycemia, which will provide further theoretical support for its improvement in the treatment of T2DM. [ABSTRACT FROM AUTHOR]

Collagen peptides (CP) obtained from collagen hydrolysis have drawn much attention for their broad bioactivities, such as antioxidant, anti-inflammatory, angiotensin-converting enzyme (ACE) and dipeptidyl peptidase-IV (DPP-IV) inhibitory activities. This study employed an in silico approach to investigate the bioactivities of CP from fish, chicken, cattle, pig, yak, sheep, and donkey. BLAST analysis of amino acid sequences showed CP from mammals had comparable bioactivities but those from fish and chicken possessed different bioactivity potential due to low protein homology. In silico hydrolysis of collagen with gastrointestinal enzymes, including trypsin, pepsin, and proteinase K showed that the number of bioactive CP from chicken (922) and mammals (737–905) was higher than that from fish (544–675) because of the lower content of proline in fish collagen, but the amount of bioactive peptides percentage to the total peptides generated for tilapia was the highest (86.4%). The most common bioactivities were ACE and DPP-IV inhibitory activities. A molecular docking study showed that Thr-Phe and Gly-Phe had the strongest binding energy to enzymes involved in ACE and DPP-IV, respectively, indicating that collagen was a good source of anti-hypotensive and anti-hypoglycaemic peptides. • BLAST analysis showed Peptides from fish and chicken possess lower bioactivities. • Chicken, donkey, and yak produced more bioactive peptides than fish. • The screened peptides were safe and did not exhibit toxicity. • Peptides TF and QF have strong affinity with ACE and DPP-IV, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Monosaccharide-induced glycation enhances the gel properties of oyster MP. • The gelling of glycated MP related to carbon number and structure of monosaccharide. • Oyster MP glycated by glucose (aldohexose) possessed the optimal gel properties. • The hydrogen bonds and hydrocarbon bonds were important binding modes. Glycation offers a promising potential to improve protein gelling properties in food industries. Therefore, the study was aimed to illustrate the effect of five monosaccharides (erythrose-aldotetrose, xylose-aldopentose, glucose-aldohexose, galactose-aldohexose, and fructose-ketohexose) with different carbon numbers and structure on the structure–gelling relationship of myofibrillar protein (MP) from oyster (Crassostrea gigas). Results showed that monosaccharides significantly increased the glycation degree of MP by increasing sulfhydryl content, forming stable tertiary conformation and decreasing surface hydrophobicity. Moreover, the gel properties of MP like gel strength, water holding capacity, water mobility were improved by alleviating aggregation including the increase of solubility and the decrease of particle sizes. Oyster MP glycated by glucose (aldohexose) possessed the optimal gel properties. Molecular docking simulation showed that hydrogen bonds and hydrocarbon bonds were the mainly non-covalent binding modes. The study will provide a theoretical basis for oyster protein glycation and expand its application on food gel. [ABSTRACT FROM AUTHOR]