Peptide Composition Research Articles

Silver Carp (Hypophthalmichthys molitrix) Scales Collagen Peptides (SCPs): Preparation, Whitening Activity Screening and Characterization

This study involves the preparation of scale collagen peptides (SCPs) with whitening activity from silver carp (Hypophthalmichthys molitrix) and their characterization and peptide sequence identification. In this article, scanning electron microscopy (SEM) was used to observe structure changes of sliver carp scales; enzymatic hydrolysis was optimized through protease screening and response surface optimization. The ultrafiltration was used to separate SCPs and the whitening activity was comprehensively evaluated using radical scavenging rate and tyrosinase-inhibiting activity, among others. An optimal component was characterized and identified using various modern spectral analysis techniques. The results showed that the surface of silver carp scales after decalcification was smooth and clear. The pepsin had the highest peptide yield and tyrosinase-inhibiting activity (90.01% and 82.25%, respectively). The optimal enzymatic hydrolysis conditions were an enzyme dosage of 16.1%, a solid-liquid ratio of 1:15.6 and a time of 4.9 h. The proportions of hydrophobic and basic amino acids in the peptide composition were 32.15% and 13.12%, respectively. Compared with SCPs2, SCPs1 (6096.68-9513.70 Da) showed better ·OH scavenging ability, tyrosinase-inhibiting activity and moisture absorption. SCPs1 was a macromolecular fragment of type I collagen with a triple helix structure, containing three peptide sequences with the potential for tyrosinase activity inhibition (AGPPGADGQTGQRGE, SGPAGIAGPAGPRGPAGPNGPPGKD and KRGSTGEQGSTGPLGMRGPRGAA). These results show that SCPs1 is a collagen peptide product with whitening potential.

Antioxidant potential of protein hydrolysates from canola (Brassica napus L.) seeds

The antioxidant potential of a protein hydrolysate depends on the composition and sequence of antioxidant peptides produced during hydrolysis and the interaction of these peptides with other oxidative compounds. There are few studies on the antioxidant potential of canola (Brassica napus L.); however, as a source rich in protein (30–40%), canola paste is suitable to produce hydrolysates with this function. The objective of this work was to obtain hydrolysates using the sequential pepsin-pancreatin (PP) system, to determine some chemical characteristics and their antioxidant potential. Limited hydrolysates with a degree of hydrolysis of less than 10 (DH < 10) were obtained for canola protein hydrolysates at 5 min of reaction (CPH5min) with 7.97% and for canola protein hydrolysates at 10 min of reaction (CPH10min) with 9.78%. Regarding its amino acid (AA) composition, a high proportion of the amino acid His was found with 21.1% for CPH5min and 22.8% for CPH10min, as well as other hydrophobic amino acids in lower concentrations. In electrophoresis, it was found that 2S napin and 12S cruciferin, typical of canola, were still present. The hydrolysates also presented a high content of phenolic compounds (CPH5min with 190 mg EAG/100 g and CPH10min with 220 mg EAG/100 g), which along with the antioxidant activity evaluated with DPPH radicals (CPH5min with 29.01% and CPH10min with 35.6%) and ABTS, (CPH5min 5.45 mM TEAC/g and CPH10min 5.45 mM TEAC/g) were higher compared to the canola protein concentrate (CPC) used as a substrate to obtain the hydrolysates.

In silico Analysis of Molecular Phylogeny of Genes Involved in the Synthesis of Bioactive Compounds in Cyanobacteria Strains Located in Tehran Cascade

Background: Cyanobacteria is an excellent candidate for discovering bioactive compounds with applications in pharmaceutical industries. Nowadays, the major bioactive metabolites isolated from cyanobacteria are polymerized, nonribosomal peptides (NRPS), or hybrids of both. Despite numerous studies on the gene distribution of bioactive compounds, no studies have been conducted on the cyanobacteria strains found in the Tehran cascade. Objectives: This monitoring study aimed to study the secondary structure of the protein and molecular phylogeny of polypeptides synthase genes and nonribosomal peptides along with the 16S rRNA gene. Methods: In this study, 20 strains of cyanobacteria found in the Tehran Cascade were identified based on a 16rRNA gene sequence. The PCR of the nonribosomal peptides (NRPS) and polyketide synthase (PKS) genes was performed using molecular techniques to analyze the phylogenetic genes responsible for secondary metabolite production. Bioinformatics software was used to predict the composition of peptides, activated amino acids, and signature sequences of the NRPS adenylation module. Finally, the strains studied in the Alborz Herbarium Microbial Culture Collection (CCC) were kept at the Azad Islamic University, Science and Research Unit. Results: The NRPS and PKS genes were found in some strains. Furthermore, the bioinformatics analyses revealed the type of natural compound, the signature sequences, and the predication of the activated amino acid. Clustering of NRPS and PKS protein sequences showed no clear phylogenetic correlation between adenylation domains and the type of activated amino acid, indicating wide diversity within adenylation domains. Conclusions: The biological analysis of polypeptide synthase and nonribosomal peptide synthetases genes may help estimate species that produce natural products and the possible role of these enzymatic complexes in the bio-synthesis of bioactive compounds in the pharmaceutical industry.

Пептиды трипсинового гидролизата молозива коров

Bovine colostrum contains biologically active substances, e.g., immunoglobulins, peptides, and cytokines, which makes it a logical component of numerous functional products. Colostrum peptides also possess antimicrobial activity. This bioavailability increases during colostrum fermentation with proteolytic enzymes. The research objective was to describe peptides isolated from the trypsic hydrolyzate supernatant of bovine colostrum and to evaluate their antimicrobial and antifungal properties.&#x0D; The supernatant of trypsin hydrolyzate of bovine colostrum was isolated by centrifugation at 3900 rpm for 7 min. The supernatant was separated by preparative chromatography. Its peptide composition was determined on a MALDI-TOF mass spectrometer, while the protein sequences were deciphered using the Mascot database. Proteins were precipitated with ammonium sulfate, and the antimicrobial activity was measured by the disk-diffusion method against gram-positive and gram-negative bacteria and dipoloid fungi. Strains were cultivated on a thick LB nutrient medium at 37°C. The antimicrobial activity was defined experimentally on Wistar rats infected intraperitoneally with Salmonella enteritidis 92. &#x0D; The trypsin hydrolyzate supernatant of bovine colostrum revealed four peptides, one of which belonged to short peptides, while the remaining three belonged to polypeptides. The isolated peptides had different molecular weights of 8.4, 6.5, 13.0, and 18 kDa. The enzymatic hydrolyzate proved bactericidal against Escherichia coli and Bacillus subtilis and demonstrated antifungal activity against Candida albicans. When rats infected with S. enteritidis 92 were administered with trypsin hydrolysate, it promoted their survival, decreased LD50, and increased the mean day of death period from 2 to 4 days.&#x0D; The research proved the antimicrobial effect of colostrum peptides and suggested their immunotropic properties. The peptides obtained from the trypsin hydrolyzate supernatant of bovine colostrum can be recommended for functional food industry as part of antimicrobial products.

Proteomic Approaches and Potential Applications in Autosomal Dominant Polycystic Kidney Disease and Fabry Disease.

Although rare, hereditary diseases, such as autosomal dominant polycystic kidney disease (ADPKD) and Fabry disease (FD) may significantly progress towards severe nephropathy. It is crucial to characterize it accurately, predict the course of the illness and estimate treatment effectiveness. A huge effort has been undertaken to find reliable biomarkers that might be useful for an early prevention of the disease progression and/or any invasive diagnostic procedures. The study of proteomics, or the small peptide composition of a sample, is a field of study under continuous development. Over the past years, several strategies have been created to study and define the proteome of samples from widely varying origins. However, urinary proteomics has become essential for discovering novel biomarkers in kidney disease. Here, the extracellular vesicles in human urine that contain cell-specific marker proteins from every segment of the nephron, offer a source of potentially valuable urinary biomarkers, and may play an essential role in kidney development and kidney disease. This review summarizes the relevant literature investigating the proteomic approaches and potential applications in the regular studies of ADPKD and FD.

Depth of Sequencing Plays a Determining Role in the Characterization of Phage Display Peptide Libraries by NGS

Next-generation sequencing (NGS) has raised a growing interest in phage display research. Sequencing depth is a pivotal parameter for using NGS. In the current study, we made a side-by-side comparison of two NGS platforms with different sequencing depths, denoted as lower-throughput (LTP) and higher-throughput (HTP). The capacity of these platforms for characterization of the composition, quality, and diversity of the unselected Ph.D.TM-12 Phage Display Peptide Library was investigated. Our results indicated that HTP sequencing detects a considerably higher number of unique sequences compared to the LTP platform, thus covering a broader diversity of the library. We found a larger percentage of singletons, a smaller percentage of repeated sequences, and a greater percentage of distinct sequences in the LTP datasets. These parameters suggest a higher library quality, resulting in potentially misleading information when using LTP sequencing for such assessment. Our observations showed that HTP reveals a broader distribution of peptide frequencies, thus revealing increased heterogeneity of the library by the HTP approach and offering a comparatively higher capacity for distinguishing peptides from each other. Our analyses suggested that LTP and HTP datasets show discrepancies in their peptide composition and position-specific distribution of amino acids within the library. Taken together, these findings lead us to the conclusion that a higher sequencing depth can yield more in-depth insights into the composition of the library and provide a more complete picture of the quality and diversity of phage display peptide libraries.

Application of steam explosion treatment on the collagen peptides extraction from cattle bone

In this study, steam explosion (SE) treatment was applied to extract collagen peptides from cattle bone. The SE treatment conditions included steam pressure: 1.5 MPa (200.43 °C), 2.0 MPa (213.85 °C), and 2.5 MPa (224.99 °C), and reaction time: 10 min, 20 min, and 30 min. With the increase of pressure and reaction time, the protein recovery rate improved, and reached to 60.5% at 2.0 MPa–30 min. SE significantly decreased the molecular weight of collagen peptides (P < 0.05) with increasing pressure and reaction time. However, at 2.5 MPa, SE darkened the sample color resulting in dark yellow. Particle size analysis and SEM images indicated that SE decreased the particle size and destroyed microstructure of cattle bone powder. FT-IR analysis showed that SE induced distinct characteristic peaks of hydroxyapatite in cattle bone powder. SE facilitated peptides release from collagen by destroying peptide bonds and enzymatic cross-links. Amino acid analysis indicated SE could not change the amino acid composition of collagen peptides. The calcium-binding ability and osteoblast proliferative activity of extracted collagen peptides were 44.7 μg/mg and 126.7% (200 μg/mL), respectively. The findings put forward data support and a scientific basis for the application and development of SE technology to collagen peptides extraction and high-value utilization of cattle bone.

Identification of novel α-glucosidase inhibitory peptides in rice wine and their antioxidant activities using in silico and in vitro analyses

Many peptides are contained in rice wine, which may have various bioactivities, and need to be investigated. The aim of this study was to identify novel peptides with high α-glucosidase inhibition and antioxidant activities in rice wine and to illustrate their underlying mechanisms. Peptide composition, α-glucosidase inhibition and antioxidant activities of the different elution fractions from macroporous resin adsorption chromatography were investigated. Potentially bioactive peptides were screened via in silico analyses and validated by in vitro experiments, and then, their mechanisms were further investigated by molecular docking and molecular dynamics simulations. Results showed that the peptides from 50% ethanol-eluted rice wine (50%-RP) exhibited strong α-glucosidase inhibition and antioxidant activities. Three novel peptides, SSLFR, QFTPR and FTYPR screened out by in silico analyses, were confirmed to have good α-glucosidase inhibition and antioxidant activities, and FTYPR exhibited the best bioactivities. These peptides could bind to ABTS and DPPH radicals and the active site of α-glucosidase through hydrogen bonding, Pi bonding and van der Waals forces. This study may not only provide new knowledge for the health effects of rice wine, but also supply theoretical bases for the development of health products of rice wine to improve its economic value.

The impact of plant diversity and vegetation composition on bumblebee colony fitness

The current decline in pollinators may disrupt ecosystems and ecosystem services with potentially harmful effects on nature and human society. While the importance of habitat loss and fragmentation, pollution and increased disease risk in driving pollinator decline has been clearly demonstrated, the impact of resource diversity is less well understood. In this study, we investigated the effect of pollen diversity and composition on reproductive success and fitness of Bombus terrestris colonies. We asked the question whether a higher plant diversity results in a more diverse diet, lower pathogen incidence and a higher colony fitness. To answer these questions, colonies of lab‐reared bumblebees were placed in species‐poor heathlands and species‐rich semi‐natural grasslands that strongly differed in plant community composition and diversity. We examined pollen loads on the bodies of foragers and identified the plant taxa present in the realized diet via DNA metabarcoding of the ITS2 marker. Liquid chromatography–mass spectrometry (LC–MS) was used to compare peptide composition of pollen samples from both habitats. Colony fitness was assessed by counting the number of sexuals produced by the colony at the end of its cycle. At the same time, colonies were examined for parasite incidence. Pollen composition and diversity on pollinators' bodies differed significantly between bees foraging in grasslands and heathlands. Concomitantly, peptide composition differed significantly between pollen samples from grasslands and heathlands. Contrary to our prediction, colonies developed significantly better in heathland sites than in grasslands. In addition, the relationship between colony fitness and pollen diversity was weak and varied between the two habitats. Pathogen incidence was very low and not affected by habitat. Overall, our results indicate that plant diversity is not necessarily a good predictor of colony fitness, and that vegetation composition and associated differences in both the quantity and quality of pollen are more important than pollen diversity per se.

Characterization and Biological Activities of In Vitro Digested Olive Pomace Polyphenols Evaluated on Ex Vivo Human Immune Blood Cells

Olive pomace (OP) represents one of the main by-products of olive oil production, which still contains high quantities of health-promoting bioactive compounds. In the present study, three batches of sun-dried OP were characterized for their profile in phenolic compounds (by HPLC-DAD) and in vitro antioxidant properties (ABTS, FRAP and DPPH assays) before (methanolic extracts) and after (aqueous extracts) their simulated in vitro digestion and dialysis. Phenolic profiles, and, accordingly, the antioxidant activities, showed significant differences among the three OP batches, and most compounds showed good bioaccessibility after simulated digestion. Based on these preliminary screenings, the best OP aqueous extract (OP-W) was further characterized for its peptide composition and subdivided into seven fractions (OP-F). The most promising OP-F (characterized for its metabolome) and OP-W samples were then assessed for their potential anti-inflammatory properties in ex vivo human peripheral mononuclear cells (PBMCs) triggered or not with lipopolysaccharide (LPS). The levels of 16 pro-and anti-inflammatory cytokines were measured in PBMC culture media by multiplex ELISA assay, whereas the gene expressions of interleukin-6 (IL-6), IL-10 and TNF-α were measured by real time RT-qPCR. Interestingly, OP-W and PO-F samples had a similar effect in reducing the expressions of IL-6 and TNF-α, but only OP-W was able to reduce the release of these inflammatory mediators, suggesting that the anti-inflammatory activity of OP-W is different from that of OP-F.

Nature-inspired protein ligation and its applications.

The ability to manipulate the chemical composition of proteins and peptides has been central to the development of improved polypeptide-based therapeutics and has enabled researchers to address fundamental biological questions that would otherwise be out of reach. Protein ligation, in which two or more polypeptides are covalently linked, is a powerful strategy for generating semisynthetic products and for controlling polypeptide topology. However, specialized tools are required to efficiently forge a peptide bond in a chemoselective manner with fast kinetics and high yield. Fortunately, nature has addressed this challenge by evolving enzymatic mechanisms that can join polypeptides using a diverse set of chemical reactions. Here, we summarize how such nature-inspired protein ligation strategies have been repurposed as chemical biology tools that afford enhanced control over polypeptide composition.

Identification of ACE I-Inhibitory Peptides Released by the Hydrolysis of Tub Gurnard (Chelidonichthys lucerna) Skin Proteins and the Impact of Their In Silico Gastrointestinal Digestion.

Tub gurnard is a highly abundant fishery species caught as a discard in the Mediterranean Sea. This work proposes its valorisation through the release of potential antihypertensive peptides and glycosaminoglycans (GAGs) through the controlled hydrolysis of tub gurnard skin proteins. Four proteases (Esperase, Alcalase, Trypsin and Pronase E) were used to obtain potent angiotensin converting enzyme I (ACE)-inhibitory hydrolysates. Peptides and GAGs were separated and evaluated for their antihypertensive potential by fluorometry. The peptide-rich fractions derived from the Esperase and Alcalase hydrolysates showed very low IC50 values (47 and 68 μg/mL, respectively). Only the GAGs from the Trypsin and Esperase hydrolysates were relevant ACE inhibitors (63 and 52% at 1 mg/mL, respectively). The peptide composition of the most potent ACE-inhibitory fractions derived from the Esperase and Alcalase hydrolysates (IC50 values of 33 and 29 μg/mL, respectively) was analysed by RP-LC-ESI-MS/MS. The analysis suggests that the ACE-inhibitory activity is related to the peptide hydrophobicity, as well as to the presence of specific residues at any of the last four C-terminal positions. The in silico gastrointestinal digestion of these fractions yielded small peptides with antihypertensive potential.

Hydrolysis of pea protein concentrate in subcritical water media with addition of citrus pectin and citric acid

Pea protein concentrate (PPC) was hydrolyzed by subcritical water with citrus pectin or citric acid to obtain bioactive peptides and amino acids. Subcritical water at 160–240 oC and 50 bar for 10–60 min was used. The degree of hydrolysis (DH) significantly increased (p < 0.05) with increasing temperature. The highest DH (64.8%) was obtained at 220 oC/50 bar/10 min with a PPC:pectin ratio of 1:1 (w/w). The dominant peptide in the hydrolysate had molecular weight of 4.1 kDa. The main nd high hydronium and hydroxide ion concamino acids in the hydrolysates were hydrophilic amino acids (45.7 g/100 g protein at 180 oC/50 bar/10 min). The DPPH- scavenging activity of protein hydrolysates using citric acid was significantly higher (p < 0.05) than the ones obtained with pectin. The hydrolysates with pectin, on the other hand, had significantly (p < 0.05) higher ferric reducing antioxidant power than the ones obtained with citric acid which was likely due to the differences in the peptide size and composition.

Biomolecular condensates formed by designer minimalistic peptides

Inspired by the role of intracellular liquid-liquid phase separation (LLPS) in formation of membraneless organelles, there is great interest in developing dynamic compartments formed by LLPS of intrinsically disordered proteins (IDPs) or short peptides. However, the molecular mechanisms underlying the formation of biomolecular condensates have not been fully elucidated, rendering on-demand design of synthetic condensates with tailored physico-chemical functionalities a significant challenge. To address this need, here we design a library of LLPS-promoting peptide building blocks composed of various assembly domains. We show that the LLPS propensity, dynamics, and encapsulation efficiency of compartments can be tuned by changes to the peptide composition. Specifically, with the aid of Raman and NMR spectroscopy, we show that interactions between arginine and aromatic amino acids underlie droplet formation, and that both intra- and intermolecular interactions dictate droplet dynamics. The resulting sequence-structure-function correlation could support the future development of compartments for a variety of applications.

Factors Influencing the Prediction Accuracy of Model Peptides in Reversed-Phase Liquid Chromatography

Hydrophobicity is an important physicochemical property of peptides in solution. As well as being strongly associated with peptide stability and aggregation, hydrophobicity governs the solution based chromatographic separation processes, specifically reversed-phase liquid chromatography (RPLC). In addition, hydrophobicity is a major physicochemical property of peptides in comparison to H-bonding, electrostatic, and aromatic properties in intermolecular interactions. However, a wide range of molecular factors can influence peptide hydrophobicity, with accurate predictions depending on specific peptide amino acid compositions, structure, and conformation. It is noticeable that peptide composition, the position of the amino acid, and its neighbouring groups play a crucial role in the elution process. In light of this, the same amino acid behaved differently depending on its position and neighbouring amino acid in the peptide chain. Extra attention should be paid to the denaturation process during the course of elution, as it has been shown to complicate and alter the elution pattern. This paper reports on the key peptide properties that can alter hydrophobicity and, consequently, the RPLC elution behaviour of the peptides, and it will conclude by proposing improved prediction algorithms for peptide elution in RPLC.

The path of proteolysis by bovine chymotrypsin

Chymotrypsin is one of the major proteases in intestinal protein digestion. Observations about the type of bonds that are hydrolysed (specificity and preference) were in the past derived from the peptide composition after digestion or hydrolysis rates of synthetic peptides. In this study, the path of hydrolysis by bovine chymotrypsin, i.e formation and degradation of peptides, were described for α-lactalbumin, β-lactoglobulin and β-casein. The peptide compositions, determined with UPLC-PDA-MS at different time points were used to determine the digestion kinetics for individual cleavage sites. It was evaluated how statements on (secondary) specificity from literature were reflected in the release kinetics of peptides. β-Lactoglobulin reached the highest degree of hydrolysis (10.9 ± 0.1 %) and was hydrolysed fastest (28 ± 1 mMpeptide bonds/s/mMenzyme), regardless of its globular (tertiary) structure. Chymotrypsin showed a preference towards aromatic amino acids, methionine and leucine, but was also tolerant to other amino acids. For the cleavage sites within this preference, ̴73% of the cleavage sites were hydrolysed with high or intermediate selectivity. For the missed cleavages within the preference, 45 % was explained by hindrance of proline, which affected hydrolysis only when in positions P3, P1′ or P2′. No clear indication (based on primary structure) was found to explain the other missed cleavages. A few cleavage sites were hydrolysed extremely efficient in α-lactalbumin (F9, F31, W104) and β-casein (W143, L163, F190). This study gave unique and quantitative insight in peptide formation and degradation by chymotrypsin in the digestion of proteins. The approach used showed potential to explore the path of hydrolysis for other proteases with less defined specificity.

Prediction of celiac disease associated epitopes and motifs in a protein.

Celiac disease (CD) is an autoimmune gastrointestinal disorder causes immune-mediated enteropathy against gluten. Gluten immunogenic peptides have the potential to trigger immune responses which leads to damage the small intestine. HLA-DQ2/DQ8 are major alleles that bind to epitope/antigenic region of gluten and induce celiac disease. There is a need to identify CD associated epitopes in protein-based foods and therapeutics. In this study, computational tools have been developed to predict CD associated epitopes and motifs. Dataset used for training, testing and evaluation contain experimentally validated CD associated and non-CD associate peptides. We perform positional analysis to identify the most significant position of an amino acid residue in the peptide and checked the frequency of HLA alleles. We also compute amino acid composition to develop machine learning based models. We also developed ensemble method that combines motif-based approach and machine learning based models. Our analysis support existing hypothesis that proline (P) and glutamine (Q) are highly abundant in CD associated peptides. A model based on density of P&Q in peptides has been developed for predicting CD associated peptides which achieve maximum AUROC 0.98 on independent data. We discovered motifs (e.g., QPF, QPQ, PYP) which occurs specifically in CD associated peptides. We also developed machine learning based models using peptide composition and achieved maximum AUROC 0.99. Finally, we developed ensemble method that combines motif-based approach and machine learning based models. The ensemble model-predict CD associated motifs with 100% accuracy on an independent dataset, not used for training. Finally, the best models and motifs has been integrated in a web server and standalone software package "CDpred". We hope this server anticipate the scientific community for the prediction, designing and scanning of CD associated peptides as well as CD associated motifs in a protein/peptide sequence (https://webs.iiitd.edu.in/raghava/cdpred/).

Hypoxia-Driven Changes in a Human Intestinal Organoid Model and the Protective Effects of Hydrolyzed Whey.

Many whey proteins, peptides and protein-derived amino acids have been suggested to improve gut health through their anti-oxidant, anti-microbial, barrier-protective and immune-modulating effects. Interestingly, although the degree of hydrolysis influences peptide composition and, thereby, biological function, this important aspect is often overlooked. In the current study, we aimed to investigate the effects of whey protein fractions with different degrees of enzymatic hydrolysis on the intestinal epithelium in health and disease with a novel 2D human intestinal organoid (HIO) monolayer model. In addition, we aimed to assess the anti-microbial activity and immune effects of the whey protein fractions. Human intestinal organoids were cultured from adult small intestines, and a model enabling apical administration of nutritional components during hypoxia-induced intestinal inflammation and normoxia (control) in crypt-like and villus-like HIO was established. Subsequently, the potential beneficial effects of whey protein isolate (WPI) and two whey protein hydrolysates with a 27.7% degree of hydrolysis (DH28) and a 50.9% degree of hydrolysis (DH51) were assessed. In addition, possible immune modulatory effects on human peripheral immune cells and anti-microbial activity on four microbial strains of the whey protein fractions were investigated. Exposure to DH28 prevented paracellular barrier loss of crypt-like HIO following hypoxia-induced intestinal inflammation with a concomitant decrease in hypoxia inducible factor 1 alpha (HIF1α) mRNA expression. WPI increased Treg numbers and Treg expression of cluster of differentiation 25 (CD25) and CD69 and reduced CD4+ T cell proliferation, whereas no anti-microbial effects were observed. The observed biological effects were differentially mediated by diverse whey protein fractions, indicating that (degree of) hydrolysis influences their biological effects. Moreover, these new insights may provide opportunities to improve immune tolerance and promote intestinal health.

Identification and virtual screening of novel anti-inflammatory peptides from broccoli fermented by Lactobacillus strains.

Lactobacillus strains fermentation of broccoli as a good source of bioactive peptides has not been fully elucidated. In this work, the peptide composition of broccoli fermented by L. plantarum A3 and L. rhamnosus ATCC7469 was analyzed by peptidomics to study the protein digestion patterns after fermentation by different strains. Results showed that water-soluble proteins such as rubisco were abundant sources of peptides, which triggered the sustained release of peptides as the main target of hydrolysis. In addition, 17 novel anti-inflammatory peptides were identified by virtual screening. Among them, SIWYGPDRP had the strongest ability to inhibit the release of NO from inflammatory cells at a concentration of 25 μM with an inhibition rate of 52.32 ± 1.48%. RFR and KASFAFAGL had the strongest inhibitory effects on the secretion of TNF-α and IL-6, respectively. At a concentration of 25 μM, the corresponding inhibition rates were 74.61 ± 1.68% and 29.84 ± 0.63%, respectively. Molecular docking results showed that 17 peptides formed hydrogen bonds and hydrophobic interactions with inducible nitric oxide synthase (iNOS). This study is conducive to the high-value utilization of broccoli and reduction of the antibiotic use.

Comparison of the generation of α-glucosidase inhibitory peptides derived from prolamins of raw and cooked foxtail millet: In vitro activity, de novo sequencing, and in silico docking

Foxtail millet prolamin has been demonstrated to have anti-diabetic effects. In this study, we compared the generation of anti-α-glucosidase peptides derived from prolamins of raw and cooked foxtail millet (PRFM and PCFM). PRFM and PCFM hydrolysates (PRFMH and PCFMH) both exhibited α-glucosidase inhibitory activity. After ultrafiltration according to molecular weight (Mw), the fraction with Mw < 3 kDa in PCFMH (PCFMH<3) showed higher α-glucosidase inhibitory activity than that in PRFMH (PRFMH<3). The composition of α-glucosidase inhibitory peptides identified by de novo sequencing in PCFMH<3 and PRFMH<3 was compared by virtual screening, combining biological activity, net charge, grand average of hydropathicity (GRAVY), and key hydrophobic amino acids (Met, Pro, Phe, and Leu). We found that the proportion of peptides with excellent α-glucosidase binding force in PCFMH<3 was higher than in PRFMH<3. Overall, cooking may positively affect the generation of peptides that perform well in inhibiting α-glucosidase derived from foxtail millet prolamin.