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.

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.

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.

Repair of Rabbit Femoral Defects with a Novel BMP2-derived Oligopeptide P24

In this study, the bioactivity of a novel BMP2-derived oligopeptide P24 was investigated by using the model of rabbit femoral defect after loaded in the biodegradable poly （lactic acid / glycolic acid / asparagic acid-co-polyethylene glycol） （PLGA-[ASP-PEG]）. A 1.5-cm unilateral segmental bone defect was created in the left femoral diaphysis in each of the 30 new zealand white rabbits. The defects of 18 legs filled with BMP2-derived peptide P24 combined with PLGA-[ASP-PEG] scaffold serves as the experimental group, and the defects in the rest 12 rabbits filled with （PLGA-[ASP-PEG]） without P24 as control group. The bone-repairing capability in the target region of the two group was grossly, radiologically, histopathologically and biomechanically evaluated 4, 8 and 12 weeks after the operation. Our results showed that in each group, primary healing of incision was achieved in the two groups. Radiographically, in experimental group, defects were filled with induced callus within 8 weeks, and a cortical bone-like structure was observed in some animals at the 12th week. According to the standardized stage of bone defect repair, 9 （64.28%） achieved grade-4 healing. In contrast, little bone formation was seen in the defects even 12 weeks after the operation, and 5 （62.50%） had grade 0 healing in this group. Histologically, tissue engineering material was mostly absorbed and cartilage was found around implants in the experimental group at the 4th week; 8 weeks after operation, the engineering material was completely absorbed, and formation of woven bone was observed and typical trabecular bone structure could be seen. In control group, 8 weeks after operation, the defect was filled with fibrous tissues, and no bone-like structure was observed. Statistical analysis showed very significant difference in biomechanical indicators between the two groups （P〈0.05）. It is concluded that new oligopeptide P24 can induce excellent bone regeneration and promote bone repair.

A synthetic oligopeptide of HDV antigen and its diagnostic application in HDV infection

A fragment of hepatitis delta antigen(HDAg),a 27-peptide,was synthesized andused to develop an ELISA for the diagnosis of hepatitis delta virus(HDV)infection.It was foundthat positive anti-HD reaction occurred in the 27-peptide coated microtiter well after a sample ofstored serum known to be anti-HD positive was added. Neutralization test revealed that the pep-tide competed with natural HDAg for anti-HD, indicating the similarity of the antigenicity be-tween the peptide and natural HDAg.The peptide was quite specific in its antigenicity withoutcross reaction with normal human or mouse serum or with human anti-HA,anti-HB or anti-HCpositive serum.When the peptide was used clinically,1 anti-HD positive case among 300 blooddonors and 21 anti-HD positive cases among 211 cases of various forms of hepatitis B were detect-ed with the 27-peptide.

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.

Size Effect on the Raman Spectra and Electronic Structure of the Glycine-alanine Oligopeptide Chains

A theoretical study on oligopeptide chains of glycine-alanine by density functional theory（DFT） is given in this paper. Raman spectra of the oligopeptide chains are examined. The geometric structures, frontier orbital, energy gap, atomic charge distribution, density of states and chemical activity of the side chain are studied at the B3LYP/6-31G（d） level. Results show that, with the number of residues increasing, vibrations of typical functional groups present Raman frequency shift, and the energy gap is gradually reduced. The HOMO and LUMO focus on the amino and carboxyl at the ends of oligopeptides. It is helpful for oligopeptides to self-assemble into chains. In addition, different residues（glycine or alanine） at the ends of chains result in the even-odd effect of orbital energy in the growth process. The size effects of physical and chemical properties only exist when the oligopeptides are shorter, and the phenomenon disappeared as the chain continues to grow.

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.

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.

Promoted Comprehensive Properties of Polyisoprene Rubber with Extremely High Fatigue Resistance Enabled by Oligopeptide Aggregates

For decades,the preparation of polyisoprene rubber that can match the comprehensive properties of natural rubber(NR)has been pursued.While sacrificial bonds have been used to promote the strength and toughness of rubbers,little is known about their effects on fatigue resistance,which is important in dynamic environments.Herein,terminal block and randomly functionalized polyisoprene rubbers tethered with di-alanine,tri-alanine and tetra-alanine were prepared.The results showed that the flow activation energy,aggregates ordering and energy dissipation of the hydrogen-bonded aggregates increase with the elongation of oligopeptide length(XA,X=2,3,4),therefore resulting in enhanced mechanical strength and toughness of corresponding samples.Comparably,the tear strengths are barely affected by oligopeptide lengths in block samples,but promoted from dipeptide to tetrapeptide in random samples,probably due to the well dispersed oligopeptide aggregates.Most importantly,it is found that the tight binding aggregates of oligopeptides are critical for the excellent fatigue resistance,which is absent in polyisoprene and natural rubber.The loose aggregates dissociate and recombine repeatedly under cyclic loading and the tight aggregates keep the network integrated and robust.Interestingly,the largest hysteresis of PIP-4A-V with the longest oligopeptide length give the lowest heat generation,which is contrary to the traditional sacrificial bonds.Overall,the oligopeptide aggregates have repeatable energy dissipation properties and cycle life comparable to or even surpassing those of the linked proteins in NR,resulting in similar tensile strength,fracture toughness,and better fatigue resistance relative to NR.This deep insight on the role of oligopeptide aggregates is very useful for the engineering rubbers served in dynamic environments.

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.

The Oligopeptide Transporters： A Small Gene Family with a Diverse Group of Substrates and Functions？

Genes in the Oligopeptide Transport family encode integral membrane proteins that are believed to trans- locate their substrates from either the extracellular environment or an organelle into the cytosol. Phylogenetic analyses of plant transporters have revealed two distant clades. the Yellow Stripe-Like （YSL） proteins and the so-called Oligopeptide Transporters （OPTs）, for which the family was named. Three categories of substrates have been identified for this family： small peptides, secondary amino acids bound to metals, and glutathione. Notably, the YSL transporters are involved in metal homeostasis through the translocation of metal-chelates, indicating a level of conservation both in biological func- tion as well as substrates. In contrast, the functions of OPT proteins seem to be less defined and, in this review, I will examine the supporting and contradictory evidence for the proposed roles of OPTs in such diverse functions as long-dis- tance sulfur distribution, nitrogen mobilization, metal homeostasis, and heavy metal sequestration through the transport of glutathione, metal-chelates, and peptides.

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.

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.

Enzyme-instructed hybrid nanogel/nanofiber oligopeptide hydrogel for localized protein delivery

Enzyme-catalysis self-assembled oligopeptide hydrogel holds great interest in drug delivery,which has merits of biocompatibility,biodegradability and mild gelation conditions.However,its application for protein delivery is greatly limited by inevitable degradation of enzyme on the encapsulated proteins leading to loss of protein activity.Moreover,for the intracellularly acted proteins,cell membrane as a primary barrier hinders the transmembrane delivery of proteins.The internalized proteins also suffer from acidic and enzymatic degradation in endosomes and lysosomes.We herein develop a proteasemanipulated hybrid nanogel/nanofiber hydrogel for localized delivery of intracellularly acted proteins.The embedded polymeric nanogels(CytoC/aNGs)preserve activity of cytochrome c(CytoC)that is an intracellular activator for cell apoptosis as a model protein against proteolysis,and do not affect the gelation properties of the protease-catalysis assembled hydrogels.The injectable hydrogel(CytoC/aNGs/Gel)serves as a reservoir to enhance intratumoral retention and realize sustainable release of CytoC/aNGs.The released CytoC/aNGs increase cellular uptake of CytoC and enhance its intracellular delivery to its target site,cytoplasm,resulting in favorable apoptosis-inducing and cytotoxic effects.We show that a single local administration of CytoC/aNGs/Gel efficiently inhibit the tumor growth in the breast tumor mouse model.

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.

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.

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.

Oligopeptide Self-Assembly:Mechanisms,Stimuli-Responsiveness,and Biomedical Applications

Oligopeptide self-assembly materials have emerged as a promising class of biomaterials with diverse applications in biomedicine.This review highlights the recent progress in comprehending the selfassembly mechanisms intrinsic to oligopeptides and their behavior in response to specific stimuli.By methodically structuring the amino acid sequence and managing external stimuli such as pH levels,redox conditions,or enzymatic activity,we can exercise unprecedented control over the self-assembly process.By controlling the self-assembly process of oligopeptides,various structures with extraordinary versatility can be obtained,including micelles,nanofibers,and coacervate droplets,each possessing modifiable mechanical and chemical properties.Furthermore,these self-assembled constructs demonstrate immense potential within varied biomedical applications.The stimuli-sensitive nature of oligopeptide assembly materials facilitates timely encapsulation and release of therapeutic cargos,consequently eliciting desired cellular responses.This approach paves the way for more precise tumor targeting,personalized medicinal treatments,and well-regulated drug dispensation.Their innate biocompatibility and proficiency in replicating the extracellular matrix(ECM)render them ideally suited for applications such as tissue engineering,wound remediation,and regenerative medicine.In summary,oligopeptide self-assembling materials show tremendous potential as adaptable platforms for cutting-edge biomedical applications,thereby bridging the divide between fundamental research and practical clinical application.