Three novel umami peptides derived from the alcohol extract of the Pacific oyster(Crassostrea gigas):identification,characterizations and interactions with T1R1/T1R3 taste receptors

Oyster(Crassostrea gigas),the main ingredient of oyster sauce,has a strong umami taste.In this study,three potential umami peptides,FLNQDEEAR(FR-9),FNKEE(FE-5),and EEFLK(EK-5),were identified and screened from the alcoholic extracts of the oyster using nano-HPLC-MS/MS analysis,i Umami-Scoring Card Method(i Umami-SCM)database and molecular docking(MD).Sensory evaluation and electronic tongue analysis were further used to confirm their tastes.The threshold of the three peptides ranged from 0.38 to 0.55 mg/m L.MD with umami receptors T1R1/T1R3 indicated that the electrostatic interaction and hydrogen bond interaction were the main forces involved.Besides,the Phe592 and Gln853 of T1R3 were the primary docking site for MD and played an important role in umami intensity.Peptides with two Glu residues at the terminus had stronger umami,especially at the C-terminus.These results contribute to the understanding of umami peptides in oysters and the interaction mechanism between umami peptides and umami receptors.

Novel umami peptides from two Termitomyces mushrooms and molecular docking to the taste receptor T1R1/T1R3

Wild edible Termitomyces mushrooms are popular in Southwest China and umami is important flavor qualities of edible mushrooms.This study aimed to understand the umami taste of Termitomyces intermedius and Termitomyces aff.bulborhizus.Ten umami peptides from aqueous extracts were separated using a Sephadex G-15 gel filtration chromatography.The intense umami fraction was evaluated by both sensory evaluation and electronic tongue.They were identified as KLNDAQAPK,DSTDEKFLR,VGKGAHLSGEH,MLKKKKLA,SLGFGGPPGY,TVATFSSSTKPDD,AMDDDEADLLLLAM,VEDEDEKPKEK,SPEEKKEEET and PEGADKPNK.Seven peptides,except VEDEDEKPKEK,SPEEKKEEET and PEGADKPNK were selectively synthesized to verify their taste characteristics.All these 10 peptides had umami or salt taste.The 10 peptides were conducted by molecular docking to study their interaction with identified peptides and the umami taste receptor T1R1/T1R3.All these 10 peptides perfectly docked the active residues in the T1R3 subunit.Our results provide theoretical basis for the umami taste and address the umami mechanism of two wild edible Termitomyces mushrooms.

MiR-107-3p/Atp6v0e1 contributes to protective effects of two selenium-containing peptides,TSeMMM and SeMDPGQQ on lead-induced neurotoxicity

Two selenium(Se)-containing peptides from Se-enriched rice,TSeMMM and SeMDPGQQ,possess neuroprotective potency against lead(Pb2+)-induced cytotoxicity.However,the crosstalk between mRNA and microRNAs(miRNA)involved in the neuroprotection mechanism remains to be elucidated.In this study,RNA-sequencing and miRNA-sequencing were used to independently identify differentially expressed mRNAs and small RNAs profiles in Pb^(2+)-treated primary fetal rat cortical neurons and then the correlated miRNA-mRNA target pairs were obtained.It was found that 34 mRNAs related to oxidative phosphorylation could be reversed by pretreatment of TSeMMM and SeMDPGQQ.The protective effect of TSeMMM and SeMDPGQQ was mediated by upregulation of miR-107-3p,which downregulates the ATPase H+transporting V0 subunit e1(Atp6v0e1)mRNA level.A zebrafish model was applied to verify the relevance between the targeted mRNA and miRNA by real-time quantitative PCR.The results indicated that miR-107-3p was a potential therapeutic target to achieve neuroprotection of Se-containing peptides via stimulation of Atp6v0e1.

Food-derived protein hydrolysates and peptides:anxiolytic and antidepressant activities,characteristics,and mechanisms

Globally,the prevalence of anxiety and depression has reached epidemic proportions.Food-derived protein hydrolysates and peptides delivered through dietary supplementation can avoid the negative risks associated with traditional pharmaceuticals while delivering superior anxiolytic and antidepressant effects.This review summarizes current research on food-derived anxiolytic and antidepressant protein hydrolysates and peptides,and subsequently analyses their physicochemical characteristics and elaborates on their mechanisms.The aim of this work is to contribute to the in-depth study and provide a theoretical foundation for the development of related products to better serve patients with anxiety and depression.

Food-derived bio-functional peptides for the management of hyperuricemia and associated mechanism

Hyperuricemia,a metabolic disorder related to uric acid metabolism dysregulation,has become a common metabolic disease worldwide,due to changes in lifestyle and dietary structure.In recent years,owing to their high activity and few adverse effects,food-derived active peptides used as functional foods against hyperuricemia have attracted increasing attention.This article aims to focus on the challenge associated with peptide-specific preparation methods development,functional components identification,action mechanism(s)clarification,and bioavailability improvement.The current review proposed recent advances in producing the food-derived peptides with high anti-hyperuricemia activity by protein source screening and matched enzymatic hydrolysis condition adjusting,increased the knowledge about strategies to search antihyperuricemia peptides with definite structure,and emphasized the necessity of combining computer-aided approaches and activity evaluations.In addition,novel action mechanism mediated by gut microbiota was discussed,providing different insights from classical mechanism.Moreover,considering that little attention was paid previously on the structure-activity relationships of anti-hyperuricemia peptides,we collected the sequences from published studies and make a preliminary summary about the structure-activity relationships,which in turn provided guides for enzymatic hydrolysis optimization and bioavailability improvement.Hopefully,this article could promote the development,application and commercialization of food-derived anti-hyperuricemia peptides in the future.

Exploring the taste presentation and receptor perception mechanism of salty peptides from Stropharia rugosoannulata based on molecular dynamics and thermodynamics simulation

The taste presentation and receptor perception mechanism of the salty peptide of Stropharia rugosoannulata were predicted and verified using peptide omics and molecular interaction techniques.The combination of aspartic acid(D)and glutamic acid(E),or peptide fragments composed of arginine(R),constitute the characteristic taste structural basis of salty peptides of S.rugosoannulata.The taste intensity of the salty peptide positively correlates with its concentration within a specific concentration range(0.25–1.0 mg/mL).The receptor more easily recognizes the first amino acid residue at the N-terminal of salty peptides and the aspartic acid residue in the peptides.GLU513,ASP707,and VAL508 are the critical amino acid residues for the receptor to recognize salty peptides.TRPV1 is specifically the receptor for recognizing salty peptides.Hydrogen bonds and electrostatic interactions are the main driving forces for the interactions between salty peptides and TRPV1 receptors.KSWDDFFTR has the most potent binding capacity with the receptor and has tremendous potential for application in sodium salt substitution.This study confirmed the taste receptor that specifically recognizes salty peptides,analyzed the receptor-peptide binding interaction,and provided a new idea for understanding the taste receptor perception of salty peptides.

Andrias davidianus bone peptides alleviates hyperuricemia-induced kidney damage in vitro and in vivo

Hyperuricemia(HUA)is a vital risk factor for chronic kidney diseases(CKD)and development of functional foods capable of protecting CKD is of importance.This paper aimed to explore the amelioration effects and mechanism of Andrias davidianus bone peptides(ADBP)on HUA-induced kidney damage.In the present study,we generated the standard ADBP which contained high hydrophobic amino acid and low molecular peptide contents.In vitro results found that ADBP protected uric acid(UA)-induced HK-2 cells from damage by modulating urate transporters and antioxidant defense.In vivo results indicated that ADBP effectively ameliorated renal injury in HUA-induced CKD mice,evidenced by a remarkable decrease in serum UA,creatinine and blood urea nitrogen,improving kidney UA excretion,antioxidant defense and histological kidney deterioration.Metabolomic analysis highlighted 14 metabolites that could be selected as potential biomarkers and attributed to the amelioration effects of ADBP on CKD mice kidney dysfunction.Intriguingly,ADBP restored the gut microbiome homeostasis in CKD mice,especially with respect to the elevated helpful microbial abundance,and the decreased harmful bacterial abundance.This study demonstrated that ADBP displayed great nephroprotective effects,and has great promise as a food or functional food ingredient for the prevention and treatment of HUA-induced CKD.

Exploration of cyclooxygenase-2 inhibitory peptides from walnut dreg proteins based on in silico and in vitro analysis

Walnut dreg protein hydrolysates(WDPHs)exhibit a variety of biological activities,however,the cyclooxygenase-2(COX-2)inhibitory peptide of WDPHs remain unclear.The aim of this study was to rapidly screen for such peptides in WDPHs through a combination of in silico and in vitro analysis.In total,1262 peptide sequences were observed by nano liquid chromatography/tandem mass spectrometry(nano LC-MS/MS)and 4 novel COX-2 inhibitory peptides(AGFP,FPGA,LFPD,and VGFP)were identified.Enzyme kinetic data indicated that AGFP,FPGA,and LFPD displayed mixed-type COX-2 inhibition,whereas VGFP was a non-competitive inhibitor.This is mainly because the peptides form hydrogen bonds and hydrophobic interactions with residues in the COX-2 active site.These results demonstrate that computer analysis combined with in vitro evaluation allows for rapid screening of COX-2 inhibitory peptides in walnut protein dregs.

Calcium-chelating peptides from rabbit bone collagen:characterization,identification and mechanism elucidation

This study aimed to characterize and identify calcium-chelating peptides from rabbit bone collagen and explore the underlying chelating mechanism.Collagen peptides and calcium were extracted from rabbit bone by instant ejection steam explosion(ICSE)combined with enzymatic hydrolysis,followed by chelation reaction to prepare rabbit bone peptide-calcium chelate(RBCP-Ca).The chelating sites were further analyzed by liquid chromatography-tandem mass(LC-MS/MS)spectrometry while the chelating mechanism and binding modes were investigated.The structural characterization revealed that RBCP successfully chelated with calcium ions.Furthermore,LC-MS/MS analysis indicated that the binding sites included both acidic amino acids(Asp and Glu)and basic amino acids(Lys and Arg),Interestingly,three binding modes,namely Inter-Linking,Loop-Linking and Mono-Linking were for the first time found,while Inter-Linking mode accounted for the highest proportion(75.1%),suggesting that chelation of calcium ions frequently occurred between two peptides.Overall,this study provides a theoretical basis for the elucidation of chelation mechanism of calcium-chelating peptides.

Virtual screening,molecular docking and identification of umami peptides derived from Oncorhynchus mykiss

Oncorhynchus mykiss is delicious and contains abundant flavor substances.However,few studies focused on umami peptides of O.mykiss.In the current work,umami peptides derived from O.mykiss were identified using virtual screening,molecular docking,and electronic tongue analysis.First,the O.mykiss protein was hydrolyzed using the PeptideCutter online enzymolysis program.Subsequently,water-soluble and toxicity screening were performed by Innovagen and ToxinPred software,respectively.The potential peptides were docked with umami receptor T1R1/T1R3.Furthermore,taste properties of potential peptides were validated by electronic tongue.Docking results suggested that the three tetrapeptide EANK,EEAK,and EMQK could enter the binding pocket in the T1R1 cavity,wherein Arg151,Asp147,Gln52,and Arg277 may play key roles in the production of umami taste.Electronic tongue results showed that the umami value of EANK,EEAK,and EMQK were stronger than monosodium glutamate.This work provides a new insight for the screening of umami peptides in O.mykiss.

The dual antimicrobial and immunomodulatory roles of host defense peptides and their applications in animal production

Host defense peptides(HDPs)are small molecules with broad-spectrum antimicrobial activities against infectious bacteria,viruses,and fungi.Increasing evidence suggests that HDPs can also indirectly protect hosts by modulating their immune responses.Due to these dual roles,HDPs have been considered one of the most promising antibiotic substitutes to improve growth performance,intestinal health,and immunity in farm animals.This review describes the antimicrobial and immunomodulatory roles of host defense peptides and their recent applications in animal production.

Antimicrobial peptides act on the rumen the performance of castrated bulls

Background Many countries have already banned the use of antibiotics in animal husbandry,making it extremely difficult to maintain animal health in livestock breeding.In the livestock industry,there is an urgent need to develop alternatives to antibiotics which will not lead to drug resistance on prolonged use.In this study,eighteen castrated bulls were randomly divided into two groups.The control group(CK)was fed the basal diet,while the antimicrobial peptide group(AP)was fed the basal diet supplemented with 8 g of antimicrobial peptides in the basal diet for the experimental period of 270 d.They were then slaughtered to measure production performance,and the ruminal contents were isolated for metagenomic and metabolome sequencing analysis.Result The results showed that antimicrobial peptides could improve the daily weight,carcass weight,and net meat weight of the experimental animals.Additionally,the rumen papillae diameter and the micropapillary density in the AP were significantly greater than those in the CK.Furthermore,the determination of digestive enzymes and fermentation parameters showed that the contents of protease,xylanase,andβ-glucoside in the AP were greater than those in the CK.However,lipase content in the CK was greater than that in the AP.Moreover,the content of acetate,propionate,butyrate,and valerate was found to be greater in AP than those in CK.The metagenomic analysis annotated 1993 differential microorganisms at the species level.The KEGG enrichment of these microorganisms revealed that the enrichment of drug resistance-related pathways was dramatically decreased in the AP,whereas the enrichment of immune-related pathways was significantly increased.There was also a significant reduction in the types of viruses in the AP.187 probiotics with significant differences were found,135 of which were higher in AP than in CK.It was also found that the antimicrobial mechanism of the antimicrobial peptides was quite specific.Seven low-abundance microorganisms(Acinetobactersp.Ac1271,Aequorivita soesokkakensis,Bacillus lacisalsi,Haloferax larsenii,Lysinibacillussp.3DF0063,Parabacteroidessp.217,Streptomycessp.So13.3)were found to regulate growth performance of the bull negatively.Metabolome analysis identified 45 differentially differential metabolites that significantly different between the CK and the AP groups.Seven upregulated metabolites(4-pyridoxic acid,Ala-Phe,3-ureidopropionate,hippuric acid,terephthalic acid,L-alanine,uridine 5-monophosphate)improve the growth performance of the experimental animals.To detect the interactions between the rumen microbiome and metabolism,we associated the rumen microbiome with the metabolome and found that negative regulation between the above 7 microorganisms and 7 metabolites.Conclusions This study shows that antimicrobial peptides can improve the growth performance of animals while resisting viruses and harmful bacteria and are expected to become healthy alternatives to antibiotics.We demonstrated a new antimicrobial peptides pharmacological model.We demonstrated low-abundance microorganisms may play a role by regulating the content of metabolites.

Cytological evaluation by Caco-2 and KU812 of non-allergenic peptides from simulated digestion of infant formula in vitro

Milk allergy is a common allergic reaction found in infants and young children,most of them appear tolerance after growing up.In this study,infant formula was digested by simulated in vitro digestion method.The potential non-allergenic peptides were further screened from undigested products by exclusion of the known epitopes fromβ-lactoglobulin(BLG)andα-lactalbumin(ALA).These potential non-allergenic peptides were synthesized and their transferability were determined by Caco-2 cell monolayer model.Finally,the potential allergenicity were evaluated by KU812 cell degranulation model.The results showed that 7 peptides were screened as non-allergenic sequences,among which were 3 from ALA and 4 from BLG.The Caco-2 cell model showed that all the synthetic peptides were absorbed and transported well.However,only peptide BLG_(107-118)showed potential allegencity by KU812 model.In conclusion,6 peptides,including ALA_(29-51),ALA_(80-90),ALA_(94-103),BLG_(1-20),BLG_(24-50),and BLG_(123-139)were evaluated as hypoallergenic peptides,which could be used for candidates of peptides inducing immune tolerance for persons with milk allergy.

Immunomodulatory effect of ethanol-soluble polypeptides from Atlantic cod (Gadus morhua)

There are many active substances in Atlantic cod(Gadus morhua)explaining the variety of biological activities.In order to study the immunomodulatory activity and the mechanism of Atlantic cod peptides at the cellular level.In this study,cod peptides were isolated by 80%ethanol extraction method,the isolated ethanol-soluble cod peptides(CP-ES)were investigated and their immunomodulatory activity was verified.Additionally,CP-ES showed lower molecular weight and more hydrophobic amino acids.CP-ES could promote the proliferation of spleen lymphocytes and T lymphocytes in mice,suggesting that CP-ES may regulate adaptive immunity.It promoted the release of NO and the expression of iNOS,TNF-α,IL-6 and IL-1βgenes in macrophages,suggesting that CP-ES may regulate innate immunity.CP-ES could promote the expression of TLR2 gene,and the peptides identified in CP-ES were docked with TLR2 to predict the peptides playing a major role in CP-ES.These results suggested that CP-ES may regulate the immune activity of both innate and adaptive lines.

Antarctic krill antioxidant peptides show inferior IgE-binding ability and RBL-2H3 cell degranulation

Enzymatic hydrolysis,isolation,and purification might make a great deal of difference in antioxidant activity and antigenicity of peptide components.This study aimed to isolate and purify antioxidant peptide components from Antarctic krill and evaluate their allergenicity of them.Electron paramagnetic resonance(EPR)spectroscopy results indicated 3-10 kDa Antarctic krill hydrolysates(AKHs)had higher DPPH and·OH radical scavenging rates.And the second component(N2-2)purified 3-10 kDa hydrolysate showed better ability to scavenge DPPH and·OH radicals(P<0.05),which were(47.43±2.18)%and(34.33±1.25)%,respectively.Additionally,indirect-ELISA results revealed that N2-1 had a weaker ability to bind specific IgE and that N2-2 had a lower binding capability to specific IgG1(P<0.05).And N2-2 had a higher EC50 value of(5.29±0.95)ng/mL(P<0.05)in cell degranulation assay,which was about 13.80 times that of Antarctic krill.Therefore,N2-2 might be the potential source of the antioxidant peptides with lower allergenicity.

Cannabidiol-Mediated Sequestration of Alzheimer’s Amyloid-β Peptides in ADDL Oligomers

Cannabidiol (CBD), one of the most studied phytocannabinoids, is non-psychotropic and can induce protective effects on the central nervous system against acute and chronic brain injury. Interestingly, CBD inhibits processes relating to amyloid beta (Aβ)-induced neurotoxicity in mouse models of Alzheimer’s disease, though the detailed molecular mechanism underlying the CBD neurotoxicity modulation is not fully understood. In this study, using atomic force microscopy, we find that CBD promotes the aggregation of Aβ peptides, enhancing the formation of Aβ oligomers, also known as Aβ-derived diffusible ligands (ADDLs). The CBD-mediated sequestration of Aβ monomers in soluble ADDLs could reduce neurotoxicity. This study highlights a possible role of CBD in modulating the formation of ADDL aggregates and provides insight into potentially neuroprotective properties of CBD in Alzheimer’s disease.

Characterization of SARS-COV-2 main protease inhibitory peptides from Ulva prolifera proteins

The main protease(M^(pro))is essential for the replication of SARS-COV-2 and therefore represents a promising anti-viral target.In this study,we screened M^(pro)inhibitory peptides from Ulva prolifera protein on in-silico proteolysis.Cytotoxicity analysis using the online toxic prediction tool ToxinPred revealed that all the peptides were non-cytotoxic.The hexapeptide(SSGFID)exhibited high M^(pro)inhibitory activity in molecular docking and its IC_(50)value was 139.40±0.82μmol/L in vitro according to fluorescence resonance energy transfer assay(FRET).Quantitative real-time(qRT-)PCR results show that SSGFID could stimulate the expression of mitosis-related factors,including nuclear factor-κB,cyclin D1,and cyclin-dependent kinase 4,to promote the proliferation of mice splenocytes.Stability study revealed that SSGFID showed resistance against pepsin and trypsin but lost D(Asp)after pretreatment at121℃ for 15 min.Besides,SSGFID was mainly transported through the Caco-2 cell monolayer by the peptide transporter PepT1 and passive-mediated transport during the transport study.Unfortunately,the peptide was also degraded by Caco-2 intracellular enzymes,and the transfer rate of intact peptide was4.2%.Furthermore,Lineweaver–Burk plots demonstrated that SSGFID possessed a mixed inhibitory characteristic with M^(pro).Our study indicated the potential of Ulva prolifera as antiviral and immuneenhancing functional food ingredients and nutraceuticals.

Active Peptides and Motifs within Collagen and Other ECM Proteins

Collagens are the most abundant proteins in mammals and form an extracellular matrix (ECM) with other components as the structural support of muscle, skin, corneas and blood vessels etc. Other than providing structural support, the ECM exhibits active communication with cells and influences many cellular processes including migration, wound healing, differentiation and cancer metastasis. Though collagen proteins contain highly repetitive primary sequences and defined tertiary structures, more and more studies have shown that many short peptides/motifs within collagen proteins play key roles in various biological processes. These short sequences are effective within triple helical structures or independently as stand-alone molecules resulting from proteolytic degradation. Besides endogenous ECM-derived peptides, many more functional peptides have been produced by tissue processing, chemical synthesis, and recombinant protein production. In this review, we summarize different peptides/motifs identified in collagen and other ECM proteins and discuss their potential for medical, personal care, and cosmetics applications.

Exploration of Related Issues on PK/PD Studies and Bioanalytical Characteristics of Peptides

Peptides play multiple functions in cellular processes and are considered an attractive paradigm for the development of novel drugs and therapeutic approaches. However, the complexity of their pharmacokinetics/pharmacodynamics and physicochemical properties presents challenges in their development. Currently, there is no single analytical method that fully meets the requirements for studying peptide drug pharmacokinetics. Interdisciplinary teams and multiple technical platforms are required to address these challenges. This article explores the pharmacokinetics, bioanalytical methods, challenges, and strategies in the development of peptide drugs. As our understanding of peptide drug pharmacokinetics and bioanalytical characteristics deepens, it will facilitate their development and provide scientific evidence for rational clinical use.

Design methods for antimicrobial peptides with improved performance

The recalcitrance of pathogens to traditional antibiotics has made treating and eradicating bacterial infections more difficult.In this regard,developing new antimicrobial agents to combat antibiotic-resistant strains has become a top priority.Antimicrobial peptides(AMPs),a ubiquitous class of naturally occurring compounds with broadspectrum antipathogenic activity,hold significant promise as an effective solution to the current antimicrobial resistance(AMR)crisis.Several AMPs have been identified and evaluated for their therapeutic application,with many already in the drug development pipeline.Their distinct properties,such as high target specificity,potency,and ability to bypass microbial resistance mechanisms,make AMPs a promising alternative to traditional antibiotics.Nonetheless,several challenges,such as high toxicity,lability to proteolytic degradation,low stability,poor pharmacokinetics,and high production costs,continue to hamper their clinical applicability.Therefore,recent research has focused on optimizing the properties of AMPs to improve their performance.By understanding the physicochemical properties of AMPs that correspond to their activity,such as amphipathicity,hydrophobicity,structural conformation,amino acid distribution,and composition,researchers can design AMPs with desired and improved performance.In this review,we highlight some of the key strategies used to optimize the performance of AMPs,including rational design and de novo synthesis.We also discuss the growing role of predictive computational tools,utilizing artificial intelligence and machine learning,in the design and synthesis of highly efficacious lead drug candidates.