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.

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.

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.

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.

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.

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.

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.

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.

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.

Characterization of natural peptides in Pheretima by integrating proteogenomics and label-free peptidomics

Pheretima,also called“earthworms”,is a well-known animal-derived traditional Chinese medicine that is extensively used in over 50 Chinese patent medicines(CPMs)in Chinese Pharmacopoeia(2020 edition).However,its zoological origin is unclear,both in the herbal market and CPMs.In this study,a strategy for integrating in-house annotated protein databases constructed from close evolutionary relationship-sourced RNA sequencing data from public archival resources and various sequencing algorithms(restricted search,open search,and de novo)was developed to characterize the phenotype of natural peptides of three major commercial species of Pheretima,including Pheretima aspergillum(PA),Pheretima vulgaris(PV),and Metaphire magna(MM).We identified 10,477 natural peptides in the PA,7,451 in PV,and 5,896 in MM samples.Five specific signature peptides were screened and then validated using synthetic peptides;these demonstrated robust specificity for the authentication of PA,PV,and MM.Finally,all marker peptides were successfully applied to identify the zoological origins of Brain Heart capsules and Xiaohuoluo pills,revealing the inconsistent Pheretima species used in these CPMs.In conclusion,our integrated strategy could be used for the in-depth characterization of natural peptides of other animal-derived traditional Chinese medicines,especially non-model species with poorly annotated protein databases.

Review on marine collagen peptides induce cancer cell apoptosis,necrosis,and autophagy by reducing oxidized free radicals

Marine collagen peptides(MCPs)are natural products prepared by hydrolyzing marine collagen protein through a variety of chemical methods or enzymes.MCPs have a range of structures and biological activities and are widely present in marine species.MCPs also have a small molecular weight,are easily modified,and absorbed by the body.These properties have attracted great interest from researchers studying antioxidant,anti-tumor,and anti-aging activities.MCPs of specific molecular weights have significant anti-tumor activity and no toxic side effects.Thus,MCPs have the potential use as anti-cancer adjuvant drugs.Free radicals produced by oxidation are closely related to human aging,cancer,arteriosclerosis,and other diseases,but their relationship with cancer is not well known.In this review,we focus on the antioxidant properties of MCPs in the treatment of cancer,highlighting their antioxidant molecular structure and potential for clinical practice.

Purifi cation and identification of anti-inflammatory peptides from sturgeon (Acipenser schrenckii) cartilage

Cartilage is a nonedible byproduct with little saleable value.However,previous studies have proposed the possibility of producing peptides from cartilage with immune function modulation potential.The current study aimed to investigate the potential anti-inflammatory activity of peptides derived from sturgeon(Acipenser schrenckii)cartilage in lipopolysaccharide(LPS)-stimulated RAW264.7 macrophages.Five peptide sequences,including four novel peptides,were identified from ethanol-soluble cartilage hydrolysates.Among these five peptides,LTGP,LLLE,LLEL and VGPAGPAGP reduced the production of nitric oxide(NO)and interleukin-6(IL-6)while increasing interleukin-10(IL-10)excretion.Transcriptome analysis suggested the inhibition of activated mitogen-activated protein kinase(MAPK)and interleukin-17(IL-17)signaling pathways after LLEL intervention.MAPK,which is involved in the IL-17 signaling pathway,was further proved to be blocked by downregulating the phosphorylation of p38,extracellular-signal regulated protein kinase(ERK),and c-jun N-terminal kinase(JNK).This novel peptide offers an attractive approach to develop functional foods.

Differential expression of antimicrobial peptides in human fungal keratitis

AIM:To analyze a series of antimicrobial peptides(AMPs)in corneal tissue from individuals with fungal keratitis(FK)during the active phase of the fungus infection and after healing.METHODS:Patients undergone lamellar keratoplasty for the treatment of severe FK or corneal scar had their corneal buttons sampled.Quantitative real-time polymerase chain reaction(PCR)was used to ascertain the gene expression of human beta-defensin(HBD)-1,-2,-3,-9,S100A7,8,9,and LL-37.RESULTS:All AMPs’messenger ribonucleic acid(mRNA)expression was considerably elevated in all samples(n=12).In contrast to controls,where HBD-2,-3,and S100A7 mRNAs were expressed at very low levels,it was discovered that HBD-1,-9,S100A8,S100A9,and LL-37 were constitutively expressed in all healed samples(n=4).HBD-1,-2-3,S100A7,and LL-37 mRNAs were significantly increased in all active FK samples(n=8).The levels of HBD-9,S100A8,and S100A9 mRNAs were moderately upregulated in all active FK samples.Subgroup comparison showed that HBD-2 was significantly increased in Fusarium keratitis samples(n=5),and LL-37 mRNAs were significantly enhanced in Aspergillus keratitis samples(n=3).Whereas there was not significantly increased of HBD-1,-3,-9,S100A7,8,9 mRNA in Aspergillus keratitis samples compared with Fusarium keratitis samples.CONCLUSION:AMPs expression is increased in active FK,but not all AMPs are equally expressed.HBD-2 and LL-37 expression levels are the highest,showing some specificity of AMP expression related to FK.Human AMPs,particularly HBD-2 may play a significant role in Fusarium keratitis and LL-37 might be the key player in Aspergillus keratitis.

Determination of egg and milk allergen in food products by liquid chromatography-tandem mass spectrometry based on signature peptides and isotope-labeled internal standard

The aim of this work was to develop a liquid chromatography-tandem mass spectrometry method for the determination of milk allergen and egg allergen in food products.Signature peptides GGLEPINFQTAADQAR,VGINYWLAHK,VLVLDTDYK,FFVAPFPEVFGK,and NAVPITPTLNR were confirmed and synthesized as the quantitative peptide of ovalbumin,α-lactalbumin,β-lactoglobulin,α_(S1)-casein andα_(S2)-casein,the relative isotope-labeled internal standards were used in the quantitative analysis.Linear range was in the range of0.5-5000.0 nmol/L for egg and milk allergen in bread,cake,cookie,rice crust and wheat flour samples with free from egg and milk,the limits of detection of milk allergens and egg allergen were in the range between0.94 mg/100 g and 56.71 mg/100 g,limits of quantification of milk allergens and egg allergen were in the range between 2.36 mg/100 g and 141.78 mg/100 g.The recoveries ranged from 76.7%to 122.8%,the relative standard deviations were in the range of 1.60%-15.60%.The developed method has been successfully used for the detection of egg and milk allergen in various food samples.