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Biosensors Mar 2022is infamous for generating hospital-acquired infections, many of which are difficult to treat due to the bacterium's multidrug resistance. A sensitive and robust...
is infamous for generating hospital-acquired infections, many of which are difficult to treat due to the bacterium's multidrug resistance. A sensitive and robust detection method of can help prevent a disease outbreak. Herein, we used cells as bait to screen a commercially available phage-displayed random peptide library for peptides that could be used to detect . The biopanning-derived peptide TSATKFMMNLSP, named KP peptide, displayed a high selectivity for the with low cross-reactivity to related Gram-negative bacteria. The specific interaction between KP peptide and lipopolysaccharide resulted in the peptide's selectivity against . Quantitative analysis of this interaction by enzyme-linked immunosorbent assay revealed that the KP peptide possessed higher specificity and sensitivity toward than commercially available anti- spp. antibodies and could detect at a detection limit of 10 CFU/mL. These results suggest that KP peptide can be a promising alternative to antibodies in developing a biosensor system for detection.
Topics: Anti-Bacterial Agents; Klebsiella pneumoniae; Microbial Sensitivity Tests; Peptides
PubMed: 35323423
DOI: 10.3390/bios12030153 -
ACS Chemical Biology Jan 2018Diabetes is a leading cause of death worldwide and results in over 3 million annual deaths. While insulin manages the disease well, many patients fail to comply with...
Diabetes is a leading cause of death worldwide and results in over 3 million annual deaths. While insulin manages the disease well, many patients fail to comply with injection schedules, and despite significant investment, a more convenient oral formulation of insulin is still unavailable. Studies suggest that glycosylation may stabilize peptides for oral delivery, but the demanding production of homogeneously glycosylated peptides has hampered transition into the clinic. We report here the first total synthesis of homogeneously glycosylated insulin. After characterizing a series of insulin glycoforms with systematically varied O-glycosylation sites and structures, we demonstrate that O-mannosylation of insulin B-chain Thr27 reduces the peptide's susceptibility to proteases and self-association, both critical properties for oral dosing, while maintaining full activity. This work illustrates the promise of glycosylation as a general mechanism for regulating peptide activity and expanding its therapeutic use.
Topics: Animals; Cell Line; Drug Design; Glucose Transporter Type 4; Humans; Insulin; Mice; Protein Engineering; Structure-Activity Relationship; Threonine
PubMed: 29090903
DOI: 10.1021/acschembio.7b00794 -
Biochimica Et Biophysica Acta.... Feb 2022Fluorescence spectroscopy is used to characterize the partition of three second-generation D,L-α-cyclic peptides to two lipid model membranes. The peptides have proven...
Fluorescence spectroscopy is used to characterize the partition of three second-generation D,L-α-cyclic peptides to two lipid model membranes. The peptides have proven antimicrobial activity, particularly against Gram positive bacteria, and the model membranes are formed of either with 1,2-dimyristoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DMPG) or its mixture with 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE), at a molar ratio of (1:1). The peptide's intrinsic fluorescence was used in the Steady State and/or Time Resolved Fluorescence Spectroscopy experiments, showing that the peptides bind to the membranes, and the extent of their partition is thereof quantified. The peptide-induced membrane leakage was followed using an encapsulated fluorescent dye. Overall, the partition is mainly driven by electrostatics, but also involves hydrophobic interactions. The introduction of a hydrocarbon tail in one of the residues of the parent peptide, CPR, adjacent to the tryptophan (Trp) residue, significantly improves the partition of the modified peptides, CPRT10 and CPRT14, to both membrane systems. Further, we show that the length of the tail is the main distinguishing factor for the extension of the partition process. The parent peptide induces very limited leakage, at odds with the peptides with tail, that promote fast leakage, increasing in most cases with peptide concentration, and being almost complete for the highest peptide concentration and negatively charged membranes. Overall, the results help the unravelling of the antimicrobial action of these peptides and are well in line with their proven high antimicrobial activity.
Topics: Anti-Bacterial Agents; Antimicrobial Peptides; Gram-Positive Bacteria; Humans; Hydrophobic and Hydrophilic Interactions; Membrane Lipids; Membranes; Peptides, Cyclic; Phosphatidylethanolamines; Phosphatidylglycerols; Spectrometry, Fluorescence
PubMed: 34506796
DOI: 10.1016/j.bbamem.2021.183729 -
Accounts of Chemical Research Mar 2016The development of sequence-specific peptidomimetics has led to a variety of fascinating discoveries in chemical biology. Many peptidomimetics can mimic primary,...
The development of sequence-specific peptidomimetics has led to a variety of fascinating discoveries in chemical biology. Many peptidomimetics can mimic primary, secondary, and even tertiary structure of peptides and proteins, and because of their unnatural backbones, they also possess significantly enhanced resistance to enzymatic hydrolysis, improved bioavailability, and chemodiversity. It is known that peptide nucleic acids (PNAs) are peptidic sequences developed for the mimicry of nucleic acids; however, their unique backbone as the molecular scaffold of peptidomimetics to mimic structure and function of bioactive peptides has not been investigated systematically. As such, we recently developed a new class of peptidomimetics, "γ-AApeptides", based on the chiral γ-PNA backbone. They are termed γ-AApeptides because they are the oligomers of γ-substituted-N-acylated-N-aminoethyl amino acids. Similar to other classes of peptidomimetics, γ-AApeptides are also resistant to proteolytic degradation and possess the potential to enhance chemodiversity. Moreover, in our scientific journey on the exploration of this class of peptidomimetics, we have discovered some intriguing structures and functions of γ-AApeptides. In this Account, we summarize the current development and application of γ-AApeptides with biological potential. Briefly, both linear and cyclic (either through head-to-tail or head-to-side-chain cyclization) γ-AApeptides with diverse functional groups can be synthesized easily on the solid phase using the synthetic protocol we developed. γ-AApeptides could mimic the primary structure of peptides, as they project the same number of side chains as peptides of the same lengths. For instance, they could mimic the Tat peptide to permeate cell membranes and bind to HIV RNA with high specificity and affinity. Certain γ-AApeptides show similar activity to the RGD peptide and target integrin specifically on the cell surface. γ-AApeptides with function akin to fMLF peptides are also identified. More importantly, we found that γ-AApeptides can fold into discrete secondary structures, such as helical and β-turn-like structures. Therefore, they could be rationally designed for a range of biological applications. For instance, γ-AApeptides can mimic host-defense peptides and display potent and broad-spectrum activity toward a panel of drug-resistant bacterial pathogens. Meanwhile, because of their stability against proteolysis and their chemodiversity, γ-AApeptides are also amenable for combinatorial screening. We demonstrate that, through combinatorial selection, certain γ-AApeptides are identified to inhibit Aβ40 peptide aggregation, suggesting their potential use as a molecular probe to intervene in Alzheimer's disease. In addition, a few γ-AApeptides identified from the γ-AApeptide library have been shown to bind to the DNA-binding domain of STAT3 and antagonize STAT3/DNA interactions. Our studies suggest that, with further studies and exploration on both structures and functions, γ-AApeptides may emerge to be a new class of peptidomimetics that play an important role in chemical biology and biomedical sciences.
Topics: Microscopy, Electron, Transmission; Peptides; Protein Conformation
PubMed: 26900964
DOI: 10.1021/acs.accounts.5b00492 -
Journal of Chemical Information and... Jul 2023Most processes at the water-membrane interface often involve protonation events in proteins or peptides that trigger important biological functions and events. This is...
Most processes at the water-membrane interface often involve protonation events in proteins or peptides that trigger important biological functions and events. This is the working principle behind the pHLIP peptide technology. A key titrating aspartate (Asp14 in ) is required to protonate to induce the insertion process, increase its thermodynamic stability when membrane-embedded, and trigger the peptide's overall clinical functionality. At the core of pHLIP properties, the aspartate p and protonation are a consequence of the residue side chain sensing the changing surrounding environment. In this work, we characterized how the microenvironment of the key aspartate residue (Asp13 in the investigated pHLIP variants) can be modulated by a simple point mutation of a cationic residue (ArgX) at distinct sequence positions (R10, R14, R15, and R17). We carried out a multidisciplinary study using pHRE simulations and experimental measurements. Fluorescence and circular dichroism measurements were carried out to establish the stability of pHLIP variants in state III and establish the kinetics of the insertion and exit of the peptide from the membrane. We estimated the contribution of the arginine to the local electrostatic microenvironment, which promotes or hinders other electrostatic players from coexisting in the Asp interaction shell. Our data indicate that the stability and kinetics of the peptide insertion and exit from the membrane are altered when Arg is topologically available for a direct salt-bridge formation with Asp13. Hence, the position of arginine contributes to fine-tuning the pH responses of pHLIP peptides, which finds wide applications in clinics.
Topics: Lipid Bilayers; Aspartic Acid; Membrane Proteins; Peptides; Hydrogen-Ion Concentration
PubMed: 37395685
DOI: 10.1021/acs.jcim.3c00360 -
The FEBS Journal May 2008Peptides function as chemical signals between cells of multicellular organisms via specific receptors on target cells. Many hormones, neuromodulators and growth factors... (Review)
Review
Peptides function as chemical signals between cells of multicellular organisms via specific receptors on target cells. Many hormones, neuromodulators and growth factors are peptides. Peptide hormones and other biologically active peptides are synthesized as higher molecular weight precursor proteins (pro-hormones), which must undergo post-translational modification to yield the bioactive peptide(s). In many instances, more than one biologically active peptide is generated from one and the same precursor. In most cases, these precursors are biologically inert and their existence is confined to the membrane-enclosed subcellular compartments where processing of the pro-hormones takes place. A class of growth factors that derive from membrane-anchored precursors which themselves are biologically active constitute an exception to this model. The list of the membrane-anchored biologically active precursors has been the subject of specialized reviews. The present review focuses on precursors other than membrane-anchored precursors, which were found to be biologically active and which often display different biological activities, and may mediate their effects via receptors independent from those of their generated peptides.
Topics: Animals; Humans; Peptide Fragments; Peptide Hormones; Protein Precursors
PubMed: 18384380
DOI: 10.1111/j.1742-4658.2008.06366.x -
Neurochemical Research Sep 2022Ischemic stroke leads to acute neuron death and forms an injured core, triggering delayed cell death at the penumbra. The impaired brain functions after ischemic stroke... (Review)
Review
Ischemic stroke leads to acute neuron death and forms an injured core, triggering delayed cell death at the penumbra. The impaired brain functions after ischemic stroke are hardly recovered because of the limited regenerative properties. However, recent rodent intervention studies manipulating the extracellular environments at the subacute phase shed new light on the regenerative potency of the injured brain. This review introduces the rational design of artificial extracellular matrix (ECM) mimics using supramolecular peptidic scaffolds, which self-assemble via non-covalent bonds and form hydrogels. The facile customizability of the peptide structures allows tuning the hydrogels' physical and biochemical properties, such as charge states, hydrophobicity, cell adhesiveness, stiffness, and stimuli responses. Supramolecular peptidic materials can create safer and more economical drugs than polymer materials and cell transplantation. We also discuss the importance of activating developmental programs for the recovery at the subacute phase of ischemic stroke. Self-assembling molecular medicine mimicking the ECMs and activating developmental programs may stand as a new drug modality of regenerative medicine in various tissues.
Topics: Extracellular Matrix; Humans; Hydrogels; Ischemic Stroke; Molecular Medicine; Peptides; Regenerative Medicine; Tissue Engineering
PubMed: 35666393
DOI: 10.1007/s11064-022-03638-5 -
Methods in Molecular Biology (Clifton,... 2008Hydrogels based on peptide self-assembly form an important class of biomaterials that find application in tissue engineering and drug delivery. It is essential to... (Review)
Review
Hydrogels based on peptide self-assembly form an important class of biomaterials that find application in tissue engineering and drug delivery. It is essential to prepare peptides with high purity to achieve batch-to-batch consistency affording hydrogels with reproducible properties. Automated solid-phase peptide synthesis coupled with optimized Fmoc (9-fluorenylmethoxy-carbonyl) chemistry to obtain peptides in high yield and purity is discussed. Details of isolating a desired peptide from crude synthetic mixtures and assessment of the peptide's final purity by high-performance liquid chromatography and mass spectrometry are provided. Beyond the practical importance of synthesis and primary characterization, techniques used to investigate the properties of hydrogels are briefly discussed.
Topics: Biocompatible Materials; Chromatography, Liquid; Drug Delivery Systems; Fluorenes; Hydrogels; Mass Spectrometry; Peptides; Tissue Engineering
PubMed: 19031061
DOI: 10.1007/978-1-59745-480-3_5 -
Chemistry (Weinheim An Der Bergstrasse,... Jun 2022A series of aromatic oligoamide foldamer sequences containing different proportions of three δ-amino acids derived from quinoline, pyridine, and benzene and possessing...
A series of aromatic oligoamide foldamer sequences containing different proportions of three δ-amino acids derived from quinoline, pyridine, and benzene and possessing varying flexibility, for example due to methylene bridges, were synthesized. Crystallographic structures of two key sequences and H NMR data in water concur to show that a canonical aromatic helix fold prevails in almost all cases and that helix stability critically depends on the ratio between rigid and flexible units. Notwithstanding subtle variations of curvature, i. e. the numbers of units per turn, the aromatic δ-peptide helix is therefore shown to be general and tolerant of a great number of sp centers. We also demonstrate canonical helical folding upon alternating two monomers that do not promote folding when taken separately: folding occurs with two methylenes between every other unit, not with one methylene between every unit. These findings highlight that a fine-tuning of helix handedness inversion kinetics, curvature, and side chain positioning in aromatic δ-peptidic foldamers can be realized by systematically combining different yet compatible δ-amino acids.
Topics: Amides; Amino Acids; Amino Acids, Aromatic; Magnetic Resonance Spectroscopy; Peptides
PubMed: 35332956
DOI: 10.1002/chem.202200538 -
Nature Communications Nov 2023Post-translational modification of proteins with polyubiquitin chains is a critical cellular signaling mechanism in eukaryotes with implications in various cellular...
Post-translational modification of proteins with polyubiquitin chains is a critical cellular signaling mechanism in eukaryotes with implications in various cellular states and processes. Unregulated ubiquitin-mediated protein degradation can be detrimental to cellular homeostasis, causing numerous diseases including cancers. Recently, macrocyclic peptides were developed that selectively target long Lysine-48-linked polyubiquitin chains (tetra-ubiquitin) to inhibit ubiquitin-proteasome system, leading to attenuation of tumor growth in vivo. However, structural determinants of the chain length and linkage selectivity by these cyclic peptides remained unclear. Here, we uncover the mechanism underlying cyclic peptide's affinity and binding selectivity by combining X-ray crystallography, solution NMR, and biochemical studies. We found that the peptide engages three consecutive ubiquitins that form a ring around the peptide and determined requirements for preferential selection of a specific trimer moiety in longer polyubiquitin chains. The structural insights gained from this work will guide the development of next-generation cyclic peptides with enhanced anti-cancer activity.
Topics: Polyubiquitin; Peptides; Peptides, Cyclic; Ubiquitin; Crystallography, X-Ray
PubMed: 37938554
DOI: 10.1038/s41467-023-43025-4