Amino Acid Sequence Of Peptide Research Articles

Construction of Peptide Library in Mammalian Cells by dsDNA-Based Strategy.

While different display technologies, represented by phage display, have been widely used in drug discovery, they still can hardly achieve function-based peptide screening, which in most cases is performed in mammalian cells. And most attempts to screen functional peptides with mammalian platforms utilized plasmids to store coding information. Our previous work established double-stranded DNAs (dsDNAs) as innovative biological parts to implement AND-gate genetic circuits in mammalian cells. In the current study, we employ dsDNAs with terminal NNK degenerate codons to implement AND-gate genetic circuits and generate peptide libraries in mammalian cells. This dsDNA-based AND-gate (DBAG) peptide library construction strategy is easy to perform, requiring only PCR reaction and cell transfection. High-throughput sequencing (HTS) and single-cell sequencing results revealed both peptide length and amino acid sequence diversity of DBAG peptide libraries. Moreover, as a feasibility test of this strategy, we identified an MDM2-interacting peptide by applying the DBAG peptide library to a mammalian cell-based two-hybrid system. Our work establishes dsDNAs with terminal degenerate codons as biological parts to build peptide libraries in mammalian cells, which may have great application potential in the future.

Comprehensive evaluation of peptide de novo sequencing tools for monoclonal antibody assembly.

Monoclonal antibodies are biotechnologically produced proteins with various applications in research, therapeutics and diagnostics. Their ability to recognize and bind to specific molecule structures makes them essential research tools and therapeutic agents. Sequence information of antibodies is helpful for understanding antibody-antigen interactions and ensuring their affinity and specificity. De novo protein sequencing based on mass spectrometry is a valuable method to obtain the amino acid sequence of peptides and proteins without a priori knowledge. In this study, we evaluated six recently developed de novo peptide sequencing algorithms (Novor, pNovo 3, DeepNovo, SMSNet, PointNovo and Casanovo), which were not specifically designed for antibody data. We validated their ability to identify and assemble antibody sequences on three multi-enzymatic data sets. The deep learning-based tools Casanovo and PointNovo showed an increased peptide recall across different enzymes and data sets compared with spectrum-graph-based approaches. We evaluated different error types of de novo peptide sequencing tools and their performance for different numbers of missing cleavage sites, noisy spectra and peptides of various lengths. We achieved a sequence coverage of 97.69-99.53% on the light chains of three different antibody data sets using the de Bruijn assembler ALPS and the predictions from Casanovo. However, low sequence coverage and accuracy on the heavy chains demonstrate that complete de novo protein sequencing remains a challenging issue in proteomics that requires improved de novo error correction, alternative digestion strategies and hybrid approaches such as homology search to achieve high accuracy on long protein sequences.

Molecular Origins of Force-Dependent Protein Complex Stabilization during Bacterial Infections.

The unbinding pathway of a protein complex can vary significantly depending on biochemical and mechanical factors. Under mechanical stress, a complex may dissociate through a mechanism different from that used in simple thermal dissociation, leading to different dissociation rates under shear force and thermal dissociation. This is a well-known phenomenon studied in biomechanics whose molecular and atomic details are still elusive. A particularly interesting case is the complex formed by bacterial adhesins with their human peptide target. These protein interactions have a force resilience equivalent to those of covalent bonds, an order of magnitude stronger than the widely used streptavidin:biotin complex, while having an ordinary affinity, much lower than that of streptavidin:biotin. Here, in an in silico single-molecule force spectroscopy approach, we use molecular dynamics simulations to investigate the dissociation mechanism of adhesin/peptide complexes. We show how the Staphylococcus epidermidis adhesin SdrG uses a catch-bond mechanism to increase complex stability with increasing mechanical stress. While allowing for thermal dissociation in a low-force regime, an entirely different mechanical dissociation path emerges in a high-force regime, revealing an intricate mechanism that does not depend on the peptide's amino acid sequence. Using a dynamic network analysis approach, we identified key amino acid contacts that describe the mechanics of this complex, revealing differences in dynamics that hinder thermal dissociation and establish the mechanical dissociation path. We then validate the information content of the selected amino acid contacts using their dynamics to successfully predict the rupture forces for this complex through a machine learning model.

Tenebrio molitor Proteins-Derived DPP-4 Inhibitory Peptides: Preparation, Identification, and Molecular Binding Mechanism.

Inhibition of dipeptidyl peptidase-4 (DPP-4) is an effective way to control blood glucose in diabetic patients. Tenebrio (T.) molitor is an edible insect containing abundant protein. T. molitor protein-derived peptides can suppress the DPP-4 activity. However, the amino acid sequence and binding mechanism of these DPP-4 inhibitory peptides remain unclear. This study used the flavourzyme for T. molitor protein hydrolysis, identified the released peptides with DPP-4 inhibitory effect, and investigated the binding interactions of these peptides with DPP-4. The results showed that flavourzyme efficiently hydrolyzed the T. molitor protein, as demonstrated by the high degree of hydrolysis, disappearance of protein bands in SDS-PAGE, and changes to protein structure. The 4-h flavourzyme hydrolysates showed a good inhibitory effect on DPP-4 (IC50 value of 1.64 mg/mL). The fragment of 1000-3000 Da accounted for 10.39% of the total peptides, but showed the strongest inhibitory effect on DPP-4. The peptides LPDQWDWR and APPDGGFWEWGD were identified from this fraction, and their IC50 values against DPP-4 were 0.15 and 1.03 mg/mL, respectively. Molecular docking showed that these two peptides interacted with the DPP-4 active site via hydrogen bonding, hydrophobic interactions, salt bridge formation, π-cation interactions, and π-π stacking. Our findings indicated that T. molitor protein-derived peptides could be used as natural DPP-4 inhibitors.

Impact of peptide permeation enhancer on tight junctions opening cellular mechanisms

The myristoylated pentapeptide, L-R5, contains an amino acid sequence of the zeta inhibitory peptide (ZIP) portion (pseudosubstrate) of protein kinase C zeta (PKC ζ). As PKC ζ is involved in the modulation of epithelial tight junctions (TJs) through the phosphorylation of TJ proteins, L-R5 was suggested to interact with the enzyme resulting in the enhancement of paracellular permeability. This study shows that L-R5 does not bind to the enzyme but interacts directly with TJ proteins. We show here that the binding of PKC ζ to occludin and its successive phosphorylation is prevented by L-R5, which leads to TJ disruption and enhanced epithelial permeability. Although L-R5 did not show any in vitro cytotoxicity, a proteomics study revealed that L-R5 interferes with other regulatory pathways, e.g., apoptosis and immune response. We suggest that structural modification of the peptide may increase the specificity TJ protein-peptide interaction.

Isolation and Identification of Antioxidative Peptide from Goose Liver Hydrolysate to Ameliorate Alcohol-Mediated Oxidative Stress Damage in HHL-5 Hepatocytes.

The aim of this study was to isolate and identify antioxidative peptide from goose liver hydrolysate (GLHP) for ameliorating oxidative stress damage by alcohol in HHL-5 hepatocytes. In this research, the target antioxidative peptides in GLHP were separated, purified, and identified via a tangential flow ultrafiltration system combined with size exclusion chromatography (SEC), ion exchange chromatography (IEC), reversed-phase liquid chromatography (RP-LC), and LC-MS/MS. The results suggested that the amino acid sequence of the target antioxidative peptide for ameliorating alcohol-mediated oxidative stress damage in HHL-5 hepatocytes was Leu-Pro-Leu-Pro-Phe-Pro (LPLPFP), which had a molecular weight of 683.41 Da, and was derived from NADH-ubiquinone oxidoreductase chain 1 in goose liver. In addition, LPLPFP was confirmed to have a satisfactory stability and maintained high hepatic protective activity in a simulated gastrointestinal digestion. Moreover, the mechanism of LPLPFP prevented against oxidative stress damage in HHL-5 hepatocytes was attributed to inhibiting the production of reactive oxide species (ROS) by upregulating genes expression in the Ahr-NQO1 signal pathway. In conclusion, these results indicated that dietary GLHP supplementation could ameliorate alcohol-mediated oxidative stress damage and provide an affordable dietary intervention strategy to prevent alcohol-mediated hepatocyte damage.

Characteristics of the enzyme-induced release of bitter peptides from wheat gluten hydrolysates.

Bitter peptides in the enzymatic hydrolysates were prepared and purified from wheat gluten using aqueous ethanol solutions and macroporous resin, which has opened a new road for the extraction and separation of bitter peptides. This report contains the release regularity of bitter peptides and the factors affecting the change of bitter intensity during enzymatic hydrolysis, providing a scientific basis for the research on debitterizing method. In this study, the effects of different degrees of hydrolysis (DH) and enzyme active sites on the bitter peptide content and bitter taste thresholds were discussed. The relationship between amino acid composition, molecular weight distribution, surface hydrophobicity and bitter taste thresholds was extensively researched. The results showed the exposure of hydrophobic amino acids and the bitterness intensity of the hydrolysates increased as the DH increased, and the bitterness of wheat gluten hydrolysates (WGHs) hydrolyzed by Alcalase was stronger than that of Trypsin. According to correlation analysis, the proportion of total hydrophobic amino acid is the first factor that affects the sensory properties of bitter peptide, and the release content of bitter peptides and the content of total bitter amino acids are the second, following by the content of peptide in the molecular weight range of 500–1,000 Da and the surface hydrophobicity. The amino acid sequence of bitter peptides from WGHs were identified and predicted using high performance liquid chromatography-mass spectrometry (HPLC-MS/MS) and bioinformatics. It was found that the molecular weight of most of the peptides was below 1,500 Da, and the Q value was higher than 5.86 kJ/mol.

Structure and functions of spexin as a new neuroendocrine signal

Spexin (SPX ) is a recently discovered endogenous peptide consisting of 14 amino acids. It was found that SPX, kisspeptin (KISS), and galanin (GAL) peptides belong to the same gene family and are also endogenous ligands of GAL2 and GAL3 receptors. The amino acid sequence of the SPX peptide is relatively conserved in vertebrates and invertebrates. The mRNA and protein of SPX are highly expressed both in peripheral organs and in the peripheral/central nervous system of mammals, birds, and fishes. Many biological roles of SPX has been found in non- mammal/mammals, including food intake, energy metabolism, reproduction, nociception, gastrointestinal motility, stress, and endocrine functions. This review collectively mentions the peptide structure of SPX, its receptors and distribution in tissues, and the biological activities of SPX on various organs.

Nonlytic cellular release of hepatitis A virus requires dual capsid recruitment of the ESCRT-associated Bro1 domain proteins HD-PTP and ALIX.

Although picornaviruses are conventionally considered ‘nonenveloped’, members of multiple picornaviral genera are released nonlytically from infected cells in extracellular vesicles. The mechanisms underlying this process are poorly understood. Here, we describe interactions of the hepatitis A virus (HAV) capsid with components of host endosomal sorting complexes required for transport (ESCRT) that play an essential role in release. We show release of quasi-enveloped virus (eHAV) in exosome-like vesicles requires a conserved export signal located within the 8 kDa C-terminal VP1 pX extension that functions in a manner analogous to late domains of canonical enveloped viruses. Fusing pX to a self-assembling engineered protein nanocage (EPN-pX) resulted in its ESCRT-dependent release in extracellular vesicles. Mutational analysis identified a 24 amino acid peptide sequence located within the center of pX that was both necessary and sufficient for nanocage release. Deleting a YxxL motif within this sequence ablated eHAV release, resulting in virus accumulating intracellularly. The pX export signal is conserved in non-human hepatoviruses from a wide range of mammalian species, and functional in pX sequences from bat hepatoviruses when fused to the nanocage protein, suggesting these viruses are released as quasi-enveloped virions. Quantitative proteomics identified multiple ESCRT-related proteins associating with EPN-pX, including ALG2-interacting protein X (ALIX), and its paralog, tyrosine-protein phosphatase non-receptor type 23 (HD-PTP), a second Bro1 domain protein linked to sorting of ubiquitylated cargo into multivesicular endosomes. RNAi-mediated depletion of either Bro1 domain protein impeded eHAV release. Super-resolution fluorescence microscopy demonstrated colocalization of viral capsids with endogenous ALIX and HD-PTP. Co-immunoprecipitation assays using biotin-tagged peptides and recombinant proteins revealed pX interacts directly through the export signal with N-terminal Bro1 domains of both HD-PTP and ALIX. Our study identifies an exceptionally potent viral export signal mediating extracellular release of virus-sized protein assemblies and shows release requires non-redundant activities of both HD-PTP and ALIX.

Characterization of novel antimicrobial peptides designed on the basis of amino acid sequence of peptides from egg white hydrolysate

Salmonella enterica subsp. enterica serotype Typhimurium (S. Typhimurium) is one of the most prevalent foodborne pathogens responsible for food poisoning and is spread through the consumption of contaminated poultry products. In this study, four antimicrobial peptides (AMPs) with varying hydrophobicity and helical structure-forming tendencies were designed and synthesized based on the amino acid sequences of peptides from egg white hydrolysate. Two of these AMPs, P1R3 (KSWKKHVVSGFFLR) and P1C (KSWKKHVVSGFFLRLWVHKK), exhibited inhibitory activity against S. Typhimurium and compromised its biofilm-forming ability. Investigation of their modes of action revealed that P1R3 and P1C interact with and permeabilize the cytoplasmic membrane of bacteria, leading to membrane potential dissipation, damage to membrane integrity, and consequent bacterial death. P1R3 also bound to S. Typhimurium DNA, resulting in DNA aggregation or precipitation. Moreover, both peptides showed negligible cytotoxicity to Vero cells, and P1C displayed significant antimicrobial activity in chicken meat. Peptides P1R3 and P1C, therefore, have the potential to be developed as promising food preservatives, especially against pathogenic S. Typhimurium.

Reprint of: A Method for the Determination of the Amino Acid Sequence in Peptides

Reprint of: A Method for the Determination of the Amino Acid Sequence in Peptides

On 'A method for the determination of amino acid sequence in peptides' by P. Edman

On 'A method for the determination of amino acid sequence in peptides' by P. Edman

Monoclonal Autoantibody Against a Cryptic Epitope on Tissue-Adherent Low-Density Lipoprotein for Molecular Imaging in Atherosclerosis

BackgroundAntibody-based constructs for molecular imaging and therapeutic delivery provide promising opportunities for the diagnosis and treatment of atherosclerosis. ObjectivesThe authors aimed to generate and characterize immunoglobulin (Ig)G monoclonal autoantibodies in atherosclerosis for targeting of novel molecular determinants. MethodsThe authors created hybridomas from an unimmunized low-density lipoprotein (LDL) receptor-deficient (Ldlr−/−) mouse and selected an IgG2b isotype autoantibody, LO9, for further characterization. ResultsLO9 reacted well with native LDL bound to immobilized matrix components and less well to oxidized LDL. LO9 binding to immobilized native LDL was not neutralized by fluid-phase native LDL, indicating an adhesion-dependent epitope. The authors localized the epitope to a 20 amino-acid peptide sequence (P5) in the globular amino-terminus of apolipoprotein B. LO9 reacted with antigen in mouse atherosclerosis and in both human stable and ruptured coronary atherosclerosis. Furthermore, in vivo near-infrared fluorescence molecular tomographic imaging, and ex vivo confocal microscopy showed that intravenously injected LO9 localized beneath endothelium of the aortic arch in Ldlr−/− mice, in the vicinity of macrophages. ConclusionsThe authors believe LO9 is the first example of an IgG autoantibody that reacts with a native LDL epitope revealed by adherence to tissue matrix. Antibodies against adherent native LDL have potential as molecular targeting agents for imaging of and therapeutic delivery to atherosclerosis.

Brain Penetrant Humanized scFv Antibody Block of P2 × 4 Receptor for Treatment of Chronic Pain

Our collaborative efforts are focused on validation of promising humanized single chain Fragment variable (hscFv) antibodies targeting a unique amino acid peptide sequence of P2 × 4 receptor (P2 × 4R). Data indicate single dose post-treatment with our newly engineered hP2 × 4 scFv antibody restores mechanical and cold pain-related behaviors to baseline in our trigeminal nerve compression model (FRICT-ION). The reversal to naïve baseline persists until experiment end at 10 weeks. Anxiety-like behaviors that develop in mice with chronic pain do not develop in hscFv antibody treated mice. We are characterizing the efficacy of lead P2 × 4R hscFv antibodies on neuronal cell-type specific activation patterns in medullary spinal V nucleus slices from Fos-TRAP(targeted recombination in active populations) mice and cultured trigeminal ganglia (TG) neurons from FRICT-ION mice. Engineered scFv antibodies feature binding affinity and activity similar to or better than monoclonal antibodies because they are much smaller in size. Thus, they are brain/nervous tissue penetrant due to their small size and have promising biotherapeutic applications for both the nervous and immune systems, now recognized as interactive in chronic pain. The ribosome display method utilized to generate the scFvs is a powerful cell-free technology widely used to select single-chain antibody fragments against the target of choice. This method is inexpensive, rapid, and was used to quickly develop repertoires of high-affinity antibodies targeting P2 × 4. In our hands the scFvs developed have high affinity in the picomolar range, superior stability and solubility. The patent was filed and published. Moving forward we currently continue evaluating these humanized P2 × 4R scFv antibodies that have strong nanomolar binding affinity, reduced self-immunogenicity, and relatively inexpensive large-scale production toward new drug application status based on the successful reversal of pain related measures and reduction of neuronal activation. This project opens new avenues for development of highly effective non-opioid biologic therapeutic interventions for chronic pain. Grant support from DoD grant W81XWH2010930 (KNW, SRAA); VA Merit grant BX002695 (KNW); NIH NIDCR R21 DE028096; NIH UG3 NS123958.

Misfolding Propensity of SAA1 Fragments: Special Focus on the Signal Peptide Region

AA amyloid is the most common form of systemic amyloidosis reported in human medicine and across animal species. AA amyloidosis is the result of over‐production by hepatocytes and aberrant processing of acute‐phase serum amyloid A1 (SAA1). Proteolytic cleavage of SAA1 is believed to play a central role in AA amyloid formation. The SAA1 protein is of 122 amino acids (aa) and undergoes a first cleavage of 18 residues consisting of the signal peptide at the N‐terminal region. The aggregation propensity of the signal peptide region has never been studied. To better understand the mechanism behind systemic amyloidosis in the SAA1 protein, we studied the misfolding propensity of the signal peptide region considering that SAA1 is going through further cleavage processes. The goal of this research was to determine the propensity of the SAA1 signal peptide region to generate fibrils. We examined the signal peptide amino acid sequence of serum amyloid A1 (SAA1) derived from different animal species. A library of the 25 peptides was designed to study the fibril formation using in silico analysis and in vitro assays. The amyloidogenic potential of each SAA1 signal peptide homolog was assessed using thioflavin T fluorescence assays, Congo red binding assays, and transmission electron microscopy. After 7 days of incubation, 22 SAA1 signal peptide fragments had the propensity to form fibrils at a concentration of 500 µM with 50% hexafluoroisopropanol at 37 ºC. The signal peptide region might be important in contributing to the misfolding of aggregation‐prone proteins. Characterizing these conformations are relevant as they may be involved in seeding intact and/or fragmented SAA1, contributing to mechanism of misfolding. This information could be important for continuation studies in the understanding of misfolding disorders.

In Silico Analysis Prediction of B-Cell Epitope as a Vaccine Candidate for SARS-CoV-2 B.1.617.2 (Delta) Variant

Background: The COVID-19 pandemic by SARS-CoV-2 has caused many losses. One way to prevent the spread of this virus is to get vaccinated. However, the latest SARS-CoV-2 variants, including variant B.1.617.2 (Delta) are doubtful to be inhibited by existing vaccines because of mutations. Therefore, we need a new vaccine candidate that is effective against this SARS-CoV-2 variant. Through an immunoinformatics approach with various software and analysis websites, vaccine candidates can be predicted in a short time.Objective: Identity, analyze, obtain, and confirm the selected B-cell epitope sequence that can be used as a vaccine candidate for the SARS-CoV-2 B.1.617.2 (Delta) variant.Methods: This research was conducted by isolating the amino acid peptide sequence in the SARS-CoV-2 B.1.617.2 (Delta) variant protein spike from the Protein Data Bank which is suspected to be an immunogenic epitope and can be used as a vaccine candidate. A Series of tests were carried out such as antigenicity, toxicity, allergenicity, and BLAST® protein to ensure that this vaccine candidate is safe for later application into the human body. The next stage is a conservation analysis to see its potential by comparing it with the SARS-CoV-2 Delta (B.1.617.2) variant spike protein sequence in Indonesia. The study ended by mapping amino acid peptides to the SARS-CoV-2 Delta (B.1.617.2) variant spike protein using the Biovia Discovery Studio Visualizer v21.1.0.20298 2020 software to ensure that the selected sequences were epitope.Results: From the five amino acid peptides that have been isolated, the FTNVYADSFVIRGDEVRQIAPGQTGKIADYNYKLPDDFT epitope sequence has good results than the others. It is probable an antigen, non-toxic, non-allergen, and non-homolog to the human body protein.Conclusion: Based on this in silico study, it was found that the FTNVYADSFVIRGDEVRQIAPGQTGKIADYNYKLPDDFT epitope sequence was the best to be used as a vaccine candidate of SARS-CoV-2 B.1.617.2 (Delta) variant.Keywords: SARS-CoV-2 B.1.617.2 (Delta) variant, B-cell epitope, vaccine, in silico, immunoinformatics.

Understanding unfolding and refolding of the antibody fragments (Fab). II. Mapping intra and inter-chain disulfide bonds using mass spectrometry

Disulfide bond formation in recombinant protein therapeutics has a significant impact on the integrity and biological activity of the drug product. Formation of the disulfide linkage is the key rate-limiting step in in vitro refolding and overall manufacturing of the antibody fragments (Fab). This investigation is focused on mapping the intra, and inter-chain disulfide bonds in the in vitro refolded antibody fragments by using mass spectrometry (MS). Biosimilar rHu Ranibizumab and rHu Certolizumab expressed using E. coli were selected for the study. Both Fabs contain ten cysteine residues leading to two intra-chain disulfide bonds on each subunit and a single inter-chain disulfide linkage. rHu Certolizumab has an additional cysteine which is unpaired and used for pegylation. The amino acid sequence in the disulfide-bonded peptides was confirmed by Collision-induced dissociation (CID), Electron transfer dissociation (ETD) and High-energy collision dissociation (HCD). The light chain (LC) intra-chain disulfide is formed between Cys23-Cys88 and Cys134-Cys194 in both the Fabs. The heavy chain (HC) intra-chain disulfides are formed between Cys22-Cys96 and Cys150-Cys206 in rHu Ranibizumab. LC and HC subunits of rHu Ranibizumab are covalently linked by disulfide linkage formed between Cys214 of LC and Cys226 of HC. This study suggests that information from multiple MS platforms and orthogonal methods for peptide fragmentation can be effectively used to map disulfide linkages in biosimilar therapeutic proteins.

Applications of Tandem Mass Spectrometry (MS/MS) in Protein Analysis for Biomedical Research.

Mass Spectrometry (MS) allows the analysis of proteins and peptides through a variety of methods, such as Electrospray Ionization-Mass Spectrometry (ESI-MS) or Matrix-Assisted Laser Desorption Ionization-Mass Spectrometry (MALDI-MS). These methods allow identification of the mass of a protein or a peptide as intact molecules or the identification of a protein through peptide-mass fingerprinting generated upon enzymatic digestion. Tandem mass spectrometry (MS/MS) allows the fragmentation of proteins and peptides to determine the amino acid sequence of proteins (top-down and middle-down proteomics) and peptides (bottom-up proteomics). Furthermore, tandem mass spectrometry also allows the identification of post-translational modifications (PTMs) of proteins and peptides. Here, we discuss the application of MS/MS in biomedical research, indicating specific examples for the identification of proteins or peptides and their PTMs as relevant biomarkers for diagnostic and therapy.

Discovery of calcium-binding peptides derived from defatted lemon basil seeds with enhanced calcium uptake in human intestinal epithelial cells, Caco-2

It is anticipated that calcium-chelating peptides may serve to enhance the absorption of calcium. This research examined defatted lemon basil seeds (DLBS) which had been treated with Alcalase under optimized parameters for the degree of hydrolysis for proteolysis, discovering that the activity for calcium-binding in a competitive condition with phosphate ion was 60.39 ± 1.545%. The purification of the hydrolysates was performed via ultrafiltration along with reversed-phase high performance liquid chromatography (RP-HPLC). Determination of the purified peptide amino acid sequence was confirmed for both peptides and reported as Ala-Phe-Asn-Arg-Ala-Lys-Ser-Lys-Ala-Leu-Asn-Glu-Asn (AFNRAKSKALNEN; Basil-1), and Tyr-Asp-Ser-Ser-Gly-Gly-Pro-Thr-Pro-Trp-Leu-Ser-Pro-Tyr (YDSSGGPTPWLSPY; Basil-2). The respective activities for calcium-binding were 38.62 ± 1.33%, and 42.19 ± 2.27%. Fluorescence spectroscopy, and fourier transform infrared spectroscopy were employed in order to assess the chelating mechanism between calcium and the peptides. It was found that the calcium ions took place through the activity of the amino nitrogen atoms and the oxygen atoms on the carboxyl group. Moreover, both of these peptides served to improve calcium transport and absorption in Caco-2 cell monolayers, depending on the concentration involved. It was revealed that the peptide-calcium complexes offered an increased calcium absorption percentage when compared to free calcium at similar concentrations. It might be concluded that the peptide within the peptide-calcium complex can promote calcium absorption through both active and passive transport pathways by increasing calcium concentration and promoting cell membrane interaction. Accordingly, DLBS protein can be considered a strong potential source of protein which can be used to produce calcium-binding peptides and might therefore play a role in the production of nutraceutical foods as a bioactive ingredient.

Peptide-Based Sensing, Logic Computing, and Information Security on the Antimonene Platform.

Peptides have higher information density than DNA and equivalent molecular recognition ability and durability. However, there are currently no reports on the comprehensive use of peptides' recognition ability and structural diversity for sensing, logic computing, information coding, and protection. Herein, we, for the first time, demonstrate peptide-based sensing, logic computing, and information security on the antimonene platform. The molecular recognition capability and structural diversity (amino acid sequence) of peptides (Pb2+-binding peptide DHHTQQHD as a model) adsorbed on the antimonene universal fluorescence quenching platform were comprehensively utilized to sense targets (Pb2+) and give a response (fluorescence turn-on) and then to encode, encrypt, and hide information. Fluorescently labeled peptides used as the recognition probe and the information carrier were quenched and hidden by the large-plane two-dimensional material antimonene and specifically bound by Pb2+ as the stego key, resulting in fluorescence recovery. The above interaction and signal change can be considered as a peptide-based sensing and steganographic process to further implement quantitative detection of Pb2+, complex logic operation, information coding, encrypting, and hiding using a peptide sequence and the binary conversion of its selectivity. This research provides a basic paradigm for the construction of a molecular sensing and informatization platform and will inspire the development of biopolymer-based molecular information technology (processing, communication, control, security).