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Phosphatidylserine (PS) and docosahexaenoic acid-phosphatidylserine (DHA-PS) have significant nutritional and biological functions, which are extensively used in functional food industries. Phospholipase D (PLD)-mediated transphosphatidylation of phosphatidylcholine (PC) or DHA-PC with l -serine, is an effective method for PS and DHA-PS preparation. However, because of the hydrolysis activity of PLD, PC and DHA-PC would be converted to the undesirable byproduct, phosphatidic acid (PA) and DHA-PA. In this study, a novel phospholipase D (PLD a2 ) was firstly cloned from Acinetobacter radioresistens a2 with high transphosphatidylation activity and no hydrolysis activity. In the PLD-catalyzed synthesis process (12 h), both the transphosphatidylation conversion rate and selectivity of PS and DHA-PS were about 100%, which is the only PLD enzyme reported with this superiority up till now. In comparison with the majority of other known PLDs, PLD a2 exerted the highest activity at neutral pH, and it was stable from pH 4.0 to pH 9.0. In addition, PLD a2 had excellent thermal stability, with an optimum reaction temperature of 40 °C and keeping more than 80% activity from 20 °C to 60 °C. The high catalytic selectivity mechanism of PLD a2 was explained by utilizing homology modeling, two-step docking, and binding energy and conformation analysis. PLD a2 ensured a stable supply of the biocatalyst with its most preponderant transphosphatidylation activity and PS selectivity, and had great potential in phospholipids industrial production. [ABSTRACT FROM AUTHOR]

This study aimed to identify saltiness-enhancing peptides from yeast protein and elucidate their mechanisms by molecular docking. Yeast protein hydrolysates with optimal saltiness-enhancing effects were prepared under conditions determined using an orthogonal test. Ten saltiness-enhancing peptide candidates were screened using an integrated virtual screening strategy. Sensory evaluation demonstrated that these peptides exhibited diverse taste characteristics (detection thresholds: 0.13–0.50 mmol/L). Peptides NKF, LGLR, WDL, NMKF, FDSL and FDGK synergistically or additively enhanced the saltiness of a 0.30% NaCl solution. Molecular docking revealed that these peptides predominantly interacted with TMC4 by hydrogen bonding, with hydrophilic amino acids from both peptides and TMC4 playing a pivotal role in their binding. Furthermore, Leu217, Gln377, Glu378, Pro474 and Cys475 were postulated as the key binding sites of TMC4. These findings establish a robust theoretical foundation for salt reduction strategies in food and provide novel insights into the potential applications of yeast proteins. • Yeast protein derived saltiness-enhancing peptide candidates were virtually screened. • NKF, LGLR, WDL, NMKF, FDSL, FDGK were sensory confirmed to enhance NaCl's saltiness. • Interaction with TMC4 via H-bond promotes the saltiness enhancement of peptides. • Leu217/Gln377/Glu378/Pro474/Cys475 were deduced as the key binding sites of TMC4. [ABSTRACT FROM AUTHOR]

[Display omitted] • Complete inactivation of PPO by 3–9 V/cm DC electric field was realized. • The inactivation kinetics conforms to Weibull model with n > 1. • Structural change of PPO in electric field was analyzed by MD simulation the first time. • The receptor binding domain of catechol in PPO was altered by DC field, and bonding energy decreased. In this study, inactivation of mushroom polyphenol oxidase (PPO) by low intensity direct current (DC) electric field and its molecular mechanism were investigated. In the experiments under 3 V/cm, 5 V/cm, 7 V/cm and 9 V/cm electric fields, PPOs were all completely inactivated after different exposure times. Under 1 V/cm, a residual activity of 11.88 % remained. The inactivation kinetics confirms to Weibull model. Under 1–7 V/cm, n value closes to a constant about 1.3. The structural analysis of PPO under 3 V/cm and 5 V/cm by fluorescence emission spectroscopy and molecular dynamics (MD) simulation showed that the tertiary structure was slightly changed with increased radius of gyration, higher potential energy and rate of C-alpha fluctuation. After exposure to the electric field, most of the hydrophobic tryptophan (TRP) residues turned to the hydrophilic surface, resulting the fluorescence red-shifted and quenched. Molecular docking indicated that the receptor binding domain of catechol in PPO was changed. PPO under electric field was MD simulated the first time, revealing the changing mechanism of the electric field itself on PPO, a binuclear copper enzyme, which has a metallic center. All these suggest that the low intensity DC electric field would be a promising option for enzymatic browning inhibition or even enzyme activity inactivation. [ABSTRACT FROM AUTHOR]

Cheese is the potential great source of umami peptides, while studies on umami peptides in cheese are scant and current sensory-guided strategies are difficult for rapid and high-throughput screening umami peptides. Herein, the peptidomics of Cheddar cheese was conducted and 6 potential umami peptides (LEEL, EKNRLNFLK, DERF, NAVPITPTLNREQ, NMAINPSKENL, GKEKVNELSK) were screened by an integrated bioinformatics approach. Peptides except LEEL were validated as umami peptides while LEEL and DERF exhibited significant umami-enhancing effects. Molecular docking revealed that hydrogen bonds formed by hydrophilic amino acids between peptides and T1R1/T1R3 are critical for the binding of umami peptides to umami receptors. Furthermore, Phe247, Gln278 of T1R1 and Pro106 of T1R3 were inferred as key binding sites. In silico gastrointestinal digestion indicated that peptides except DERF have hypoglycemic and hypotensive potential. This work lays the foundation for high-throughput umami peptide screening and advances to understand the umami mechanism of cheese. • Peptidomics and bioinformatics were jointly used to screen umami peptides. • Six novel umami/umami-enhancing peptides were identified from Cheddar cheese. • Peptide-T1R1/T1R3 H-bonds formed by hydrophilic AAs are vital for umami perception. • Phe247, Gln278 of T1R1 and Pro106 of T1R3 were also key binding sites. • The other 5 peptides except DERF have hypoglycemic and hypotensive potential. [ABSTRACT FROM AUTHOR]

• Virtual strategies were integrated for high-throughput screening of umami peptides. • Six novel umami peptides CN, SM, CRD, GESMTDGF, MS and DGC were identified. • CRD, GESMTDGF, DGC had higher umami intensity and obvious umami-enhancing effects. • Umami-tasting mechanism of peptides was partly revealed by docking with T1R1/T1R3. • H-bonds formed by hydrophilic AAs of T1R1/T1R3 play key roles in umami perception. This study aimed to rapidly and precisely discover novel umami peptides from porcine type I collagen using virtual screening, sensory evaluation and molecular docking simulation. Porcine type I collagen was hydrolyzed in silico and six umami peptide candidates (CN, SM, CRD, GESMTDGF, MS, DGC) were shortlisted via umami taste, bioactivity, toxicity, allergenicity, solubility and stability predictions. The sensory evaluation confirmed that these peptides exhibited umami taste, with CRD, GESMTDGF and DGC displaying higher umami intensity and significant umami-enhancing effects in 0.35% sodium glutamate solution. Molecular docking predicted that Ser 276/384/385 of T1R1 and Asn68, Val277, Thr305, Ser306, Leu385 of T1R3 may also play critical roles in binding umami peptides. The umami taste of peptides may be perceived mainly through the formation of hydrogen bonds with the hydrophilic amino acids of T1R1/T1R3. This work provided a robust procedure and guidance to develop novel umami peptides from food byproducts. [ABSTRACT FROM AUTHOR]

• Seven XO inhibitory peptides were screened from shrimp via docking and BLAST. • YNITGW (IC 50 = 9.78 ± 0.13 mM) exhibited the greatest XO inhibitory activity. • Hydrogen bond and π-π stacking played a significant role between peptides with XO. • Insertion of Trp in the middle position of peptide could enhance the activity. Xanthine oxidase (XO) inhibitory peptides are safer than conventional pharmacological therapy in relieving hyperuricemia. However, traditional enzymatic hydrolysis, separation, and purification techniques for bio-active peptide preparation are time-consuming, inefficient, and labor-intensive. In this study, molecular docking and BLAST were used to virtually screen XO inhibitory peptides from whole protein sequences of Pacific white shrimp according to the bio-active peptides database, and the structure of peptides was optimized based on the structure-effective relationship. Seven new XO inhibitory peptides were virtual screened rapidly from Pacific white shrimp, and YNITGW (IC 50 = 9.78 ± 0.13 mM) showed the strongest activity. The results of YNITGW optimization showed that the insertion of Trp residue in the middle position of peptides could effectively enhance the activity. This study revealed that screening and optimizing peptides by molecular docking were a novel and feasible method to obtain bio-active peptides. [ABSTRACT FROM AUTHOR]

• Oyster-derived xanthine oxidase inhibitory peptides were first reported. • Three novel xanthine oxidase inhibitory peptides were obtained. • Reveal the mechanism of action of peptides with xanthine oxidase. • A series of designed xanthine oxidase inhibitory peptides were obtained. • Through rational design, the activity of peptides is greatly improved. Xanthine oxidase (XO) inhibitory peptides are secure and efficient functional food ingredients for treating or alleviating hyperuricemia (HUA). In this study, ultrafiltration and molecular exclusion chromatography were used to separate and purify enzymatic lysate of oyster protein, three novel peptides (ALSGSW, GGYGIF and MAIGLW) with strong XO inhibitory activity were screened by LC-MS/MS identification and molecular docking technology. Then, the mechanism of action between peptides and the XO was revealed by molecular docking technology, and the structure of the peptide was rationally designed on this basis. The results showed that replacing N -terminal Gly of peptide GGYGIF with Trp can significantly improve its XO inhibition rate, and peptides formed by the simple structure amino acid was connected to the aromatic amino acids has preferable inhibitory activity. These results showed that oyster was a good source of XO peptide inhibitors, molecular docking technology was an effective tool for obtaining highly active peptides. [ABSTRACT FROM AUTHOR]

This study aimed to isolate and investigate five novel xanthine oxidase (XO) inhibitory peptides FF, YF, WPW, WPDARG and YNVTGW from alkaline protease hydrolyzate (F0) of Pacific cod processing by-product bone-flesh mixture (CBFM 2 2 CBFM: Pacific cod processing by-product bone-flesh mixture.). F0 was separated by dextran gel chromatography to obtain F1, F2, F3, F4 and F5 components. The components with the highest XO inhibitory activity were analyzed and identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the peptides were further screened by molecular docking using Autodock Vina. The results showed that the F4 component had the highest XO inhibitory activity, with a molecular weight ranging from 200 to 600 Da. Five novel XO inhibitory peptides FF, YF, WPW, WPDARG and YNVTGW were obtained with IC 50 values of 0.80 mM, 0.52 mM, 1.68 mM, 0.40 mM and 0.23 mM, respectively. According to the results of molecular docking, peptides having at least one aromatic amino acid are more favorable to occupy the catalytic core of XO, reducing its catalytic activity. The amino acids Thr1010 and Phe914 in the XO active pocket interact with peptides. Overall, novel peptides from CBFM have the potential to be used as a natural uric acid reducing ingredient in functional and health foods. • Peptides were obtained by enzymatic hydrolysis of cod by-products. • Molecular docking software was used for targeted screening of active peptides. • The obtained active peptides contain at least one end of the aromatic amino acid. • Most active peptides form π-π stacking effect with xanthine oxidase 914Phe. [ABSTRACT FROM AUTHOR]

Okadaic acid (OA), dinophysistoxin-1 (DTX-1), and dinophysistoxin-2 (DTX-2) are the main diarrheic shellfish poisons (DSPs). Detection methods to achieve simultaneous detection of the three toxins are urgently needed. In this paper, a terminal fixation design proposed in our previous study was further explored to engineer an aptamer with group-specific recognition ability from an original aptamer binding to one target. Both molecular docking assay and biolayer interferometry assay were applied to reveal the binding mechanisms between three DSPs and the engineered aptamer. Then, a label-free colorimetric aptasensor by fabricating the aptamer with AuNPs@Fe2+ nanozyme was constructed, which provided a wide linear detection range (0.4688–7.5 nM), a very low limit of detection (LOD, 86.28 pM), and good recoveries (96.02–104.9%) when analyzing DSPs in seawater and scallop samples, indicating the engineered aptamer and the developed aptasensor had great potential in recognizing and detecting multiple DSPs in real world. [Display omitted] • A group-specific terminal-fixed aptamer was engineered for three DSPs. • The engineered aptamer showed high affinity at nM level towards the three DSPs. • The aptamer was fabricated with AuNPs@Fe2+ to develop a colorimetric aptasensor. • The aptasensor achieved simultaneous detection of the DSPs with high sensitivity. • The study can be referred to develop multiple-functional aptamers/aptasensors. [ABSTRACT FROM AUTHOR]