Structural Characterization and Biological Activity of Oligopeptides from Isochrysis zhanjiangensis:Based on Quantum Mechanics,Molecular Docking and in Vitro Experiments

DAPTMGY(DTY)is an oligopeptide derived from marine microalgae with proven potential to combat oxidative stress in previous research.The composition,ordering,and active sites of amino acids play a key role in activity studies and are also the research trends in recent years.As an oligopeptide with a molecular weight of less than 1000 Da,DTY is of great significance to explore the active site and structure-activity relationship.This study used quantum mechanics to optimize DTY’s structure and predict the active site through molecular orbits,energy,and charge.In addition,an LPS-treated HUVEC cell was established as an oxidative-stress model.DTY could reduce mitochondrial oxidative stress and inhibit ROS production by enhancing the antioxidant enzymes SOD,GPX,and HO-1.Moreover,it was confirmed to inhibit inflammation and apoptosis through the NF-κB and MAPK signaling pathways.Lastly,the correlation of the oligopeptide DTY’s active site and antioxidative-stress activity was verified by molecular docking,showing that hydrogen bonding is the main force,which was also the main factor for antioxidant activity.

A PRELIMINARY STUDY OF THE WATER—SOLUBLE OLIGOPEPTIDES AND AMINO ACIDS OF GINSENG

γ-Amino butyric acid(GABA)and several γ-glutamyl oligopeptides were isolated and identified from water-extract of ginseng.

OLIGOPEPTIDES FROM THE ROOTS OF ASTER TATARICUS L. f.

Two new oligopeptides, Asterin A and B, have been isolated from the roots of Aster tataricus L. f., and their structures were elucidated on the basis of spectroscop- ic, chemical and enzymatic methods.

HPLC of Amino Acids and Oligopeptides by Pre-Column Fluorescence Derivatization with 9-Acridine Formyl Chloride

A highly sensitive HPLC method for the detection of amino acids and oligopeptides with 9-acridine formyl chloride by pre-column fluorescence derivatization has been developed. Glycine, glycylglycine, histidine, triglycine and glutathione were separated on a reversed-phase C-18 column with methanol-water-triethylamine eluent, derivatization and chromatographic conditions were optimized. The five derivatives were eluted in 28 min with a good reproducibility. Linear range of the calibration graph was 0.08-260 nmol/ml(-1). The relative standard deviations(n=6) are < 5%. Detection limits (signal-to-noise ratio=3) for the five derivatives are 20-40 fmol.

Structure-activity Relationships of Vasorelaxing Effect of Polyarginine Oligopeptides

Based on the EDRF(endothelium derived relaxing factor)-like effects for polyarginine Arg-Arg-oH was selected as the lead compound and its derivatives Arg-Arg- OCH_3.Arg Arg-Arg-OH,HO-ArgCOCH_2CH_2COArg-OH,HO-ArgCOCH_2COArg-OH,were synthesized.These substances showed on bioassay various degrees of vasorelaxant activities. With protection for the C-terminal of Arg-Arg-OH with a methyl ester.the vasorelaxing ac- tivitv was decreased.In contrast.when the N-terminal of Arg-OH was protected with mal- onic acid or butane diacid.the biological activites were lower than those of Arg-Arg-OH due to the lowered metabolic rate.With protection of N-terminal of Arg-Arg-OH with L-Arg residue.Arg-Arg-Arg-OH was obtained,which showed a vasorelaxing activity better than that of Arg-Arg-OH.The bioactivities observed on the Wister's rats for the former com- pound become the experimental basis for prodrug design of EDRF.

Isoflavone Aglycones and Oligopeptides in Lactic Acid-Fermented Soy Milk Differentially Regulate Lipid Metabolism-Related Gene Expression

We previously investigated the physiological effect of an ethanol extract of fermented soymilk on rats and clarified that this extract modulated their hepatic lipid metabolism. Although the soy isoflavones and oligopeptides are representative functional components of the ethanol extract, it remained unclear whether these substances share a role in lipid metabolism modulation. Therefore, we attempted to clarify the effects of isoflavones and oligopeptides in lactic acid-fermented soymilk on lipid metabolism-related gene expression in rats and HepG2 cells. The fermented soymilk extract had a higher isoflavone aglycone content than the soymilk extract. Sevenweek-old male Sprague-Dawley rats were fed an AIN-93G diet, a diet plus 70% soymilk ethanol extract, or a diet plus 70% fermented soymilk ethanol extract for 5 weeks. Although both the soymilk and fermented soymilk ethanol extracts did not significantly affect plasma and hepatic lipid profiles, the expression levels of the genes encoding CYP7a1 and SREBP-2 were significantly upregulated in the livers of rats fed with the fermented soymilk extract. Whereas isoflavone aglycones upregulated CYP7a1-encoding gene expression in HepG2, oligopeptides in soymilk and fermented soymilk downregulated this expression. Oligopeptides in fermented soymilk downregulated the expression stronger than that observed with soymilk. On the other hand, no significant change in FAS expression was observed in the livers of rats fed the fermented soymilk extract. Although isoflavone aglycones did not affect FAS expression in HepG2 cells, oligopeptides in fermented soymilk downregulated FAS expression. The downregulation of FAS with oligopeptides from fermented soymilk was stronger than that from soymilk. In the present animal experiment, the effect on reduction of fat synthesis was not found because of insufficient amount of peptides derived from digestion of soy protein. These results suggest that isoflavone aglycones increase CYP7a1 gene expression, whereas oligopeptides decrease FAS expression. Isoflavone glycosides and proteins in soymilk were converted to isoflavone aglycones and oligopeptides by lactic acid fermentation, respectively, and these functional components independently improved the lipid metabolism. In the present study, it was found that isoflavone aglycones and oligopeptides in fermented soymilk differentially regulate hepatic lipid metabolism-related gene expression. Therefore, the consumption of fermented soymilk containing isoflavone aglycones and soy oligopeptides might prevent dyslipidemia more effectively than that of any other soy food. Fermented soymilk is a superior functional food modulating lipid metabolism.

High Fischer ratio oligopeptides in food:sources,functions and application prospects

High Fischer ratio oligopeptides(HFROs)are a group of oligopeptides containing high levels of branched-chain amino acids(BCAA)and low levels of aromatic amino acids(AAA).HFROs have received a lot of attention as they are believed to have significant physiological activities,including antioxidant,liver damage repair,anti-fatigue,anti-tumor and energy supply to the body.HFROs are available from a wide range of sources and both plant and animal proteins can be used to prepare HFROs but the physiological tolerability and rejection of special populations needs to be considered.Enzymatic hydrolysis is the most common method for the preparation of HFROs,but optimization of the separation and purification process is still needed in the future.Diseases caused by disruptions in the balance of BCAA and AAA in the blood,such as hepatic encephalopathy,can be treated by supplementing HFROs with drugs or food.In addition,HFROs are able to reduce fatigue feedback and assist in the treatment of phenylketonuria at the molecular nutrient level.The aim of this review is to review recent research on HFROs and provide new perspectives on the high value use of crops and the development of novel functional and special medical purpose foods.

Serum metabolic effects of corn oligopeptides with 7-day supplementation on early post-surgery primary liver cancer patients: a double-blind randomized controlled trial

Background:Liver cancer as the main leading cancer has caused heavy burdens globally.The prognosis of liver cancer is closely related with postoperative nutrition support.Corn oligopeptides(COPs)are protein hydrolysates produced by enzymatic treatments,which have shown potential bioactivities,such as inhibiting angiotensin I-converting enzyme,resisting lipid peroxidation and anti-oxidant.However,the correlation between COPs and liver cancer patients is still unknown and the potential mechanism of COPs on liver cancer is unclear as well.The aim of this study was to assess effects of 7-day intervention of COPs after surgery on liver function and serum metabolic profiles of liver cancer patients.Methods:Patients were assigned into COPs intervention group(n=50)and control group(n=91)for 7 days.Investigations were scheduled at 1st day and 7th day after liver resection surgery respectively,mainly including anthropometric,biochemical indexes and liquid chromatography-mass spectrometry(LC/MS)analysis.Results:Seven-day supplementation of COPs on early post-surgery liver cancer patients down-regulated levels of alanine aminotransferase,aspartate aminotransferase,total bilirubin,direct bilirubin and up-regulated prothrombin time activity and prealbumin levels.LC/MS analysis revealed metabolic signatures including regulation of 16 metabolites,which was closely related with two metabolic pathways(nicotinate and nicotinamide metabolism,fatty acid metabolism).Conclusions:COPs supplementation has displayed the potentials on alleviating the injury of liver function and it may be due to regulation of fatty acid metabolism,nicotinate and nicotinamide metabolism,lipid peroxidation and anti-inflammatory action.More researches are warranted in future to confirm the exact mechanisms.

Bat-derived oligopeptide LE6 inhibits the contact-kinin pathway and harbors anti-thromboinflammation and stroke potential

Thrombosis and inflammation are primary contributors to the onset and progression of ischemic stroke.The contact-kinin pathway,initiated by plasma kallikrein(PK)and activated factor XII(FXIIa),functions bidirectionally with the coagulation and inflammation cascades,providing a novel target for therapeutic drug development in ischemic stroke.In this study,we identified a bat-derived oligopeptide from Myotis myotis(Borkhausen,1797),designated LE6(Leu-Ser-Glu-Glu-Pro-Glu,702 Da),with considerable potential in stroke therapy due to its effects on the contact kinin pathway.Notably,LE6 demonstrated significant inhibitory effects on PK and FXIIa,with inhibition constants of 43.97μmol/L and 6.37μmol/L,respectively.In vitro analyses revealed that LE6 prolonged plasma recalcification time and activated partial thromboplastin time.In murine models,LE6 effectively inhibited carrageenan-induced mouse tail thrombosis,FeCl3-induced carotid artery thrombosis,and photochemically induced intracerebral thrombosis.Furthermore,LE6 significantly decreased inflammation and stroke injury in transient middle cerebral artery occlusion models.Notably,the low toxicity,hemolytic activity,and bleeding risk of LE6,along with its synthetic simplicity,underscore its clinical applicability.In conclusion,as an inhibitor of FXIIa and PK,LE6 offers potential therapeutic benefits in stroke treatment by mitigating inflammation and preventing thrombus formation.

Syntheses of fluoroalkyl derivatives of two biologically active oligopeptides

Fluoroalkyl derivatives of two biologically active oligopeptides [(m-CF3)Tyr(1)]-Leu-enkephalin, [(m-C2F4Cl)Tyr(1)]-Leu-enkephalin and [(m-COCF2Cl)Tyr(2)]-melanocyte-stimulating hormone releasing hormone have been synthesized. Studies on the activities of these peptides are underway.

Synthesis and anti-HIV-1 activity of the conjugates of gossypol with oligopeptides and D-glucosamine

A series of novel gossypol derivatives were synthesized and screened for their in vitro anti-HIV- 1I activity. The results showed that replacing the aldehyde groups of gossypol with certain oligopeptides and Dglucosamine not only reduced the cytotoxicity of gossypol derivatives but also enhanced their antiviral activity against HIV-1. Interestingly, D-glucosamine derivative of gossypol that lacked the COONa group also exhibited the same potent anti-HIV-1 activity as oligopeptide derivatives with the COONa group. These compounds blocked the entry of HIV-1ⅢB into target cell. which was similar to T20. Furthermore, the molecular docking analysis rationalized their anti-HIV-1 activity. The results also implied that certain oligopeptides and D-glucosamine were important moities to prepare gossypol derivatives as HIV- 1 entry inhibitors besides certain amino acids.

Ultra-small nanodots coated with oligopeptides providing highly negative charges to enhance osteogenic differentiation of hBMSCs better than osteogenic induction medium

For bone regenerative engineering,it is a promising method to form skeletal tissues differentiating from human bone morrow mesenchyme stem cells(hBMSCs).However,it is still a critical challenge to efficiently control ostogenesis and clearly reveal the influence factor.To this end,the fluorescent gold nanodots(Au NDs) with highly negative charges as osteogenic induction reagent are successfully synthesized,which display better than commercial osteogenic induction medium through the investigations of ALP activity(2.5 folds) and cytoskeleton staining(1.5 folds).Two kinds of oligopeptides with different bio-structures(cysteine,Cys and glutathione,GSH) are selected for providing surficial charges on Au NDs.It is revealed that Au-Cys with more negative charges(-51 mV) play better role than Au-GSH(-19 mV) in osteogenic differentiation,when both of them have same size(~2 nm),sphere shape and show similar cell uptake amount.To explore deeply,osteogenesis related signaling pathways are monitored,revealing that the enhancement of osteogenic differentiation was through autophagy signaling pathway triggered by Au-Cys.And the promotion of highly negative charges in osteogenic diffe rentiation was further proved via sliver nanodots(Ag NDs,Ag-Cys and Ag-GSH) and carbon nanodots(CDs,Cys-CDs and GSH-CDs).This work indicates part of insights during hBMSCs differentiation and provides a novel strategy in osteogenic differentiation process.

Synthesis of O -Phosphorylated Oligopeptides Using Phosphoramidite

Reversible protein phosphorylation is of great importance in the regulation of many cellular processes. Structurally well defined compounds are needed for the study of the roles of the phospho proteins in biological processes. In this paper, O phosphorylated oligopeptides were synthesized using bis alkyloxy N,N dialkylphosphoramidite reacting with the oligopeptide followed by oxidation. Many hydroxyl groups in oligopeptides can be phosphorylated in one step.

CRISPR/Cas9-mediated knockout of SLC15A4 gene involved in the immune response in bovine rumen epithelial cells

The objective of this study was to determine the role of SLC15A4 in the muramyl dipeptide(MDP)-mediated inflammatory response of bovine rumen epithelial cells(BRECs).First,changes in the m RNA expression of proinflammatory factor genes in BRECs following 10μg m L^(–1)MDP treatments were examined.RT-q PCR results showed that the expression of pro-inflammatory factor(IL-1β,IL-6,and TNF-α)m RNAs were significantly increased under MDP stimulation(P<0.001).Moreover,SLC15A4-Knockout(SLC15A4-KO)cells were obtained through lentivirus packaging,transfection,screening,and cell monoclonal culture.In order to gain further insight into the potential function of SLC15A4,we utilized transcriptome data,which revealed a change in the genes between WT-BRECs and SLC15A4-KO.Five down-regulated pro-inflammatory genes and 13 down-regulated chemokine genes related to the inflammatory response were identified.Meanwhile,the down-regulated genes were mostly enriched in the nuclear factorκB(NF-κB)and mitogen-activated protein kinase(MAPK)signaling pathways.The results of RT-q PCR also verified these detected changes.To further determine the mechanism of how WT and SLC15A4-KO BRECs are involved in inflammatory responses,we investigated the inflammatory responses of cells exposed to MDP.WT-BRECs and SLC15A4-KO were treated with a culture medium containing 10μg m L^(–1)MDP,in comparison to a control without MDP.Our results show that SLC15A4-KO BRECs had reduced the expression of genes(IL-6,TNF-α,CXCL2,CXCL3,CXCL9,and CCL2)and proteins(p-p65 and p-p44/42)from the MDP-mediated inflammatory response compared to WT-BRECs(P<0.05).In this experiment,CRISPR-Cas9 was used to KO the di/tripeptide transporter SLC15A4,and its role was confirmed via the MDP-induced inflammatory response in BRECs.This work will provide a theoretical basis for studying the pro-inflammatory mechanism of MDP and its application in the prevention and treatment of subacute rumen acidosis in dairy cows.

POLYMER SCAFFOLDS BEARING AZOBENZENE-POTENTIAL FOR OPTICAL INFORMATION STORAGE

The fundamental optical storage mechanism of the laser light eddressable azobenzene moiety is briefly introduced.A modular and flexible synthesis design furnishes polyester matrices covalently integrating cyanoazobenzene in regularlyspaced side chains. Thin films of these materials are particularly well suited for holographic storape. Notable figures of meritsof liquid crystalline polyesters are response time to blue-green laser light of the order of nanoseconds, storage capacityexpressed as 5000 lines/mm, and high, permanent (almost nine years) diffraction efficiency of the order of 50% or greater,and erasability, The implications of the main chain nature for polyester morphology and for the permanency of the inducedanisotropy are discussed, The design and methods of preparation of other significantly different polymer scaffolds supportingcyanoazobenzene are elaborated. Oligopeptides always result in amorphous materials, whereas copolymethacrylates anddendritic or hyperbranched polyesters provide some materials that exhibit liquid crystallinity. However, none of these scaffolds affords materials that result in permanent anisotropy when exposed to interfering laser light.

UNIQUE ORAL DRUG DELIVERY SYSTEM

An oral drug delivery system using proteinoid microspheres is discussed with respect to itsunique dependence on pH. It has been found that certain drugs such as insulin and heparin canbe encapsulated in proteinoid spheres at stomach pH's (1--3). These spheres also dissemble atintestinal pH's (6--7) releasing the drug for absorption. Using this technique low molecularweight heparin and human growth hormone have been orally delivered successfully to severalanimal species. Future work has been proposed to study the interaction and binding of thespecific drugs with synthesized oligopeptides.

Effect of Cooking Methods on the Chemical Compounds Associated with Umami Taste in Duck Breast Meat

Dry-curing,wet-curing,stewing and marinating are sequential Chinese traditional meat-processing methods dating back thousands of years ago.However,little information is available about the contribution of each processing stage to the umami taste in duck breast meat.Therefore,effects of those meat-processing methods on umami taste related chemical compounds were determined in this study.Dry-curing significantly increased free amino acids,oligopeptides and nucleotides and nucleotides degradation products(P<0.05),however,in the following wet-curing,stewing and marinating stages,the percentages of inosine and hypoxanthine were gradually declined.Electronic tongue and principle component analysis results revealed the difference between dry-cured/wet-cured duck breast meat and marinated/stewed duck breast meat was due to the increase of free amino acids,oligopeptides and inosine monophosphate.Therefore,dry-curing is an important stage in meat processing,not only it produces a pool of taste related compounds,it also stimulates the enzyme activities in the muscle.Meanwhile,in the stewing stage,the umami taste profile of duck breast meat was gradually established.We can conclude that dry-curing and stewing are the two crucial stages to form the umami taste profile in duck breast meat.

Spatial structure of beta-amyloid Aβ_(1-40) in complex with a biological membrane model

The spatial structure of beta-amyloid Aβ1-40 in complex with sodium dodecyl sulfate micelles as a model membrane system was investigated by 1H-1H two-dimensional NMR (TOCSY, NOESY) spectroscopy and molecular dynamic method calculations. On the basis of NOE and chemical shifts changes data, spatial structure of the complex beta-amyloid-model of the cell surface membrane was obtained.

Computational Exploration of Conformations of Glycine-Arginine and a Deduced Model on Global Minimum Configurations of Dipeptides in Gas Phase

An extensive computational study on the conformations of gaseous dipeptide glycine- arginine, GlyArg, has been performed. A large number of trail structures were generated by systematically sampling the potential energy surface （PES） of OlyArg. The trial structures were successively optimized with the methods of PM3, HF/3-21G＊, BHandHLYP/6-31G＊ and BHandHLYP/6-311＋＋G＊＊ in order to reliably find the low energy conformations. The eonformational energies were finally determined with the methods of BHandHLYP, cam- B3LYP, B97D, and MP2 using the basis set of 6-311＋＋G（3df,3pd）. The results establish firmly that gaseous GlyArg exists primarily in its canonical form, in sharp contrast with ArgGly that adopts the zwitterionic form. Important data such as the rotational constants, dipole moments, vertical ionization energies, temperature distributions and IR spectra of the low energy conformers are represented for the understanding of the future experiments. Moreover, considering the global minima of all amino acids and many dipeptides, combined with the hydrophobicities of amino acids, a model predicting whether the global minimum configuration of a dipeptide is canonical or zwitterionic is developed.

An Extracellular Oligopeptide Permease May Be a Potential Virulence Factor of Vibrio harveyi

An oligopeptide permease A(OppA)was purified from the extracellular product of Vibrio harveyi SF-1.The molecular weight of the purified protein was estimated to be 58 kDa on SDS-PAGE.The purified protein showed phospholipase C activity at the optimal values of temperature 50℃ and pH 8.0.The enzymatic activity decreased when the temperature increased to 40℃.The N-terminal sequence of the purified protein was determined as ADVPAGTKLA,which is similar to that of OppA.The OppA pre-cursor gene was cloned from the genome of V.harveyi SF-1.The gene consisted of 1665 base pairs and encoded a 554 amino acid polypeptide,which showed a high similarity to those of the OppAs of V.harveyi and other Vibrio species.The gene was subcloned into pET-28a(+)and expressed in Escherichia coli.The expressed recombinant protein was purified by Ni-NTA metal affinity chro-matography.The expressed recombinant protein showed a 58 kDa band on SDS-PAGE and exhibited phospholipase C activity with the optima of temperature 50℃ and pH 8.0.The purified protein was toxic to the flounder gill cells.An OppA mutant of V.harveyi SF-1 was constructed by homologous recombination.The mutant strain was less virulent when it was intraperitoneally inoculated to zebra fish,with the LD50 of 5.46×105 CFU fish-1,compared to 3.11×104 CFU fish-1 of the wild-type strain,which indicated that the OppA might play an important role in the pathogenicity of V.harveyi.