Insulin is a key hormone involved in the regulation of overall energetic homeostasis of the organism. The dimeric character of the receptor for insulin evokes ideas about its activation or inhibition with peptide dimers that could either trigger or block the structural transition of the insulin receptor, leading to its activation. Herewith, we present the chemical engineering and biological characterization of several series of insulin dimers or dimers of specific peptides that should be able to bind receptors for insulin or insulin growth factor 1. The hormones or peptides in the dimers were interconnected with different linkers, consisting of triazole moieties and 3, 6, 8, 11, or 23 polyethylene glycol units. The prepared dimers were weaker in binding to insulin receptors than human insulin. However, some of the insulin dimers showed preferential binding specificity toward the isoform A of the insulin receptor, and the insulin dimers also stimulated the insulin receptor more strongly than would be consistent with their binding affinities. Our results suggest that designing insulin dimers may be a promising strategy for modulating the ability of the hormone to activate the receptor or to alter its specificity toward insulin receptor isoforms.
- MeSH
- inzulin metabolismus MeSH
- lidé MeSH
- peptidy * chemie MeSH
- polyethylenglykoly MeSH
- protein - isoformy MeSH
- receptor inzulinu * metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Insulin is a peptide responsible for regulating the metabolic homeostasis of the organism; it elicits its effects through binding to the transmembrane insulin receptor (IR). Insulin mimetics with agonistic or antagonistic effects toward the receptor are an exciting field of research and could find applications in treating diabetes or malignant diseases. We prepared five variants of a previously reported 20-amino acid insulin-mimicking peptide. These peptides differ from each other by the structure of the covalent bridge connecting positions 11 and 18. In addition to the peptide with a disulfide bridge, a derivative with a dicarba bridge and three derivatives with a 1,2,3-triazole differing from each other by the presence of sulfur or oxygen in their staples were prepared. The strongest binding to IR was exhibited by the peptide with a disulfide bridge. All other derivatives only weakly bound to IR, and a relationship between increasing bridge length and lower binding affinity can be inferred. Despite their nanomolar affinities, none of the prepared peptide mimetics was able to activate the insulin receptor even at high concentrations, but all mimetics were able to inhibit insulin-induced receptor activation. However, the receptor remained approximately 30% active even at the highest concentration of the agents; thus, the agents behave as partial antagonists. An interesting observation is that these mimetic peptides do not antagonize insulin action in proportion to their binding affinities. The compounds characterized in this study show that it is possible to modulate the functional properties of insulin receptor peptide ligands using disulfide mimetics.
- MeSH
- disulfidy chemie MeSH
- inzulin * metabolismus MeSH
- peptidy chemie MeSH
- receptor inzulinu * MeSH
- Publikační typ
- časopisecké články MeSH
The rise of CuI-catalyzed click chemistry has initiated an increased demand for azido and alkyne derivatives of amino acid as precursors for the synthesis of clicked peptides. However, the use of azido and alkyne amino acids in peptide chemistry is complicated by their high cost. For this reason, we investigated the possibility of the in-house preparation of a set of five Fmoc azido amino acids: β-azido l-alanine and d-alanine, γ-azido l-homoalanine, δ-azido l-ornithine and ω-azido l-lysine. We investigated several reaction pathways described in the literature, suggested several improvements and proposed several alternative routes for the synthesis of these compounds in high purity. Here, we demonstrate that multigram quantities of these Fmoc azido amino acids can be prepared within a week or two and at user-friendly costs. We also incorporated these azido amino acids into several model tripeptides, and we observed the formation of a new elimination product of the azido moiety upon conditions of prolonged couplings with 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate/DIPEA. We hope that our detailed synthetic protocols will inspire some peptide chemists to prepare these Fmoc azido acids in their laboratories and will assist them in avoiding the too extensive costs of azidopeptide syntheses. Experimental procedures and/or analytical data for compounds 3-5, 20, 25, 26, 30 and 43-47 are provided in the supporting information. © 2017 The Authors Journal of Peptide Science published by European Peptide Society and John Wiley & Sons Ltd.
- MeSH
- alkyny chemie MeSH
- aminokyseliny chemická syntéza MeSH
- azidy chemie MeSH
- ethylaminy chemie MeSH
- fluoreny chemická syntéza chemie MeSH
- močovina analogy a deriváty chemie MeSH
- peptidy chemická syntéza MeSH
- syntetická chemie okamžité shody metody MeSH
- triazoly chemie MeSH
- Publikační typ
- časopisecké články MeSH
The peptide named codesane (COD), consisting of 18 amino acid residues and isolated from the venom of wild bee Colletes daviesanus (Hymenoptera : Colletidae), falls into the category of cationic α-helical amphipathic antimicrobial peptides. In our investigations, synthetic COD exhibited antimicrobial activity against Gram-positive and Gram-negative bacteria and Candida albicans but also noticeable hemolytic activity. COD and its analogs (collectively referred to as CODs) were studied for the mechanism of their action. The interaction of CODs with liposomes led to significant leakage of calcein entrapped in bacterial membrane-mimicking large unilamellar vesicles made preferentially from anionic phospholipids while no calcein leakage was observed from zwitterionic liposomes mimicking membranes of erythrocytes. The preference of CODs for anionic phospholipids was also established by the blue shift in the tryptophan emission spectra maxima when the interactions of tryptophan-containing COD analogs with liposomes were examined. Those results were in agreement with the antimicrobial and hemolytic activities of CODs. Moreover, we found that the studied peptides permeated both the outer and inner cytoplasmic membranes of Escherichia coli. This was determined by measuring changes in the fluorescence of probe N-phenyl-1-naphthylamine and detecting cytoplasmic β-galactosidase released during the interaction of peptides with E. coli cells. Transmission electron microscopy revealed that treatment of E. coli with one of the COD analogs caused leakage of bacterial content mainly from the septal areas of the cells.
- MeSH
- antibakteriální látky chemická syntéza izolace a purifikace farmakologie MeSH
- Escherichia coli účinky léků metabolismus ultrastruktura MeSH
- fluorescence MeSH
- fosfolipidy metabolismus MeSH
- hemolýza účinky léků MeSH
- hydrofobní a hydrofilní interakce MeSH
- kationické antimikrobiální peptidy genetika izolace a purifikace farmakologie MeSH
- liposomy metabolismus MeSH
- molekulární sekvence - údaje MeSH
- permeabilita buněčné membrány účinky léků MeSH
- racionální návrh léčiv MeSH
- sekundární struktura proteinů MeSH
- sekvence aminokyselin MeSH
- transmisní elektronová mikroskopie MeSH
- tryptofan chemie MeSH
- včelí jedy chemie genetika izolace a purifikace farmakologie MeSH
- včely genetika MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The antimicrobial 40-amino-acid-peptide lucifensin was synthesized by native chemical ligation (NCL) using N-acylbenzimidazolinone (Nbz) as a linker group. NCL is a method in which a peptide bond between two discreet peptide chains is created. This method has been applied to the synthesis of long peptides and proteins when solid-phase synthesis is imcompatible. Two models of ligation were developed: [15+25] Ala-Cys and [19+21] His-Cys. The [19+21] His-Cys method gives lower yield because of the lower stability of 18-peptide-His-Nbz-CONH2 peptide, as suggested by density functional theory calculation. Acetamidomethyl-deprotection and subsequent oxidation of the ligated linear lucifensin gave a mixture of lucifensin isomers, which differed in the location of their disulfide bridges only. The dominant isomer showed unnatural pairing of cysteines [C1-6], [C3-5], and [C2-4], which limits its ability to form α-helical structure. The activity of isomeric lucifensin toward Bacillus subtilis, Staphylococcus aureus, and Micrococcus luteus was lower than that of the natural lucifensin. The desired product native lucifensin was prepared from this isomer using a one-pot reduction with dithiotreitol and subsequent air oxidation in slightly alkaline medium.
- MeSH
- antiinfekční látky * chemická syntéza chemie farmakologie MeSH
- defensiny * chemická syntéza chemie farmakologie MeSH
- grampozitivní bakterie růst a vývoj MeSH
- kationické antimikrobiální peptidy * chemická syntéza chemie farmakologie MeSH
- sekundární struktura proteinů MeSH
- Publikační typ
- časopisecké články MeSH
A novel antimicrobial peptide, designated macropin (MAC-1) with sequence Gly-Phe-Gly-Met-Ala-Leu-Lys-Leu-Leu-Lys-Lys-Val-Leu-NH2 , was isolated from the venom of the solitary bee Macropis fulvipes. MAC-1 exhibited antimicrobial activity against both Gram-positive and Gram-negative bacteria, antifungal activity, and moderate hemolytic activity against human red blood cells. A series of macropin analogs were prepared to further evaluate the effect of structural alterations on antimicrobial and hemolytic activities and stability in human serum. The antimicrobial activities of several analogs against pathogenic Pseudomonas aeruginosa were significantly increased while their toxicity against human red blood cells was decreased. The activity enhancement is related to the introduction of either l- or d-lysine in selected positions. Furthermore, all-d analog and analogs with d-amino acid residues introduced at the N-terminal part of the peptide chain exhibited better serum stability than did natural macropin. Data obtained by CD spectroscopy suggest a propensity of the peptide to adopt an amphipathic α-helical secondary structure in the presence of trifluoroethanol or membrane-mimicking sodium dodecyl sulfate. In addition, the study elucidates the structure-activity relationship for the effect of d-amino acid substitutions in MAC-1 using NMR spectroscopy.
- MeSH
- antibakteriální látky chemická syntéza chemie farmakologie MeSH
- antifungální látky chemická syntéza chemie farmakologie MeSH
- Bacillus subtilis účinky léků MeSH
- erytrocyty účinky léků MeSH
- Escherichia coli účinky léků MeSH
- kationické antimikrobiální peptidy chemie izolace a purifikace farmakologie MeSH
- Micrococcus luteus účinky léků MeSH
- mikrobiální testy citlivosti MeSH
- molekulární modely MeSH
- Pseudomonas aeruginosa účinky léků MeSH
- Staphylococcus aureus účinky léků MeSH
- včelí jedy chemie izolace a purifikace farmakologie MeSH
- včely chemie MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The infrared (IR), vibrational circular dichroism (VCD), and electronic circular dichroism (ECD) spectra of short cationic sequential peptides (L-Lys-L-Ala-L-Ala)(n) (n = 1, 2, and 3) were measured over a range of temperatures (20-90 degrees C) in aqueous solution at near-neutral pH values in order to investigate their solution conformations and thermally induced conformational changes. VCD spectra of all three oligopeptides measured in the amide I' region indicate the presence of extended helical polyproline II (PPII)-like conformation at room temperature. UV-ECD spectra confirmed this conclusion. Thus, the oligopeptides adopt a PPII-like conformation, independent of the length of the peptide chain. However, the optimized dihedral angles phi and psi are within the range -82 to -107 degrees and 143-154 degrees , respectively, and differ from the canonical PPII values. At elevated temperatures, the observed intensity and bandshape variations in the VCD and ECD spectra show that the PPII-like conformation of the Lys-Ala-Ala sequence is still preferred, being in equilibrium with an unordered conformer at near-neutral pH values within the range of temperatures from 20 to 90 degrees C. This finding was obtained from analysis of the temperature-dependent spectra using the singular value decomposition method. The study presents KAA-containing oligopeptides as conformationally stable models of biologically important cationic peptides and proteins.
Glycopeptide dendrimers containing different types of tumor associated-carbohydrate antigens (T(N), TF, sialyl-T(N), sialyl-TF, sialyl-Le(x), sialyl-Le(a) etc.) were used in diagnosis and therapy of different sorts of cancer. These dendrimeric structures with incorporated T-cell epitopes and adjuvants can be used as antitumor vaccines. Best results were obtained with multiantigenic vaccines, containing, e.g. five or six different TAAs. The topic of TAAs and their dendrimeric forms at molecular level are reviewed, including structure, syntheses, and biological activities. Use of glycopeptide dendrimers as antiviral vaccines against HIV and influenza is also described. Their syntheses, physico-chemical properties, and biological activities are given with many examples.
- MeSH
- adjuvancia imunologická terapeutické užití MeSH
- antigeny sacharidové asociované s nádorem chemie klasifikace MeSH
- dendrimery diagnostické užití chemie terapeutické užití MeSH
- financování organizované MeSH
- glykopeptidy diagnostické užití chemie terapeutické užití MeSH
- HIV infekce terapie MeSH
- imunoterapie metody MeSH
- lidé MeSH
- molekulární sekvence - údaje MeSH
- nádory diagnóza terapie MeSH
- protinádorové vakcíny chemie terapeutické užití MeSH
- sacharidové sekvence MeSH
- syntetické vakcíny diagnostické užití chemie terapeutické užití MeSH
- vakcíny proti AIDS chemie terapeutické užití MeSH
- vakcíny proti chřipce chemie terapeutické užití MeSH
- virové nemoci diagnóza terapie MeSH
- virové vakcíny chemie terapeutické užití MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- přehledy MeSH
The present study has two main objectives. The first is to characterize antimicrobial peptide (AMP) cryptdin-4 (Crp-4) interactions with biological membranes and to compare those interactions with those of magainin 2. The second is to combine the complementary experimental approaches of laser scanning microscopy (LSM), ellipsometry, and Z-scan fluorescence correlation spectroscopy (FCS) to acquire comprehensive information on mechanisms of AMP interactions with supported phospholipid bilayers (SPBs)-a popular model of biological membranes. LSM shows appearance of inhomogeneities in spatial distribution of lipids in the bilayer after treatment with Crp-4. Ellipsometric measurements show that binding of Crp-4 does not significantly change the lipid structure of the bilayer (increase in adsorbed mass without a change in thickness of adsorbed layer). Furthermore, Crp-4 slows the lateral diffusion of lipids within the membrane as shown by Z-scan FCS. All changes of the bilayer induced by Crp-4 can be partially reversed by flushing the sample with excess of buffer. Bilayer interactions of magainin 2 are significantly different, causing large loss of lipids and extensive damage to the bilayer. It seems likely that differences in peptide mode of action, readily distinguished using these combined experimental methods, are related to the distinctive beta-sheet and alpha-helical structures of the respective peptides.
Glycopeptide dendrimers are branched structures containing both carbohydrates and peptides. Various classes of these compounds differing in composition and structure are mentioned, together with their practical use spanning from catalysis, transport vehicles to synthetic vaccines. The main stress is given to glycopeptide dendrimers, namely multiple antigen glycopeptides (MAGs). In MAGs, the core, branches or both are composed of amino acids or peptides. Other classes of glycodendrimers (PAMAM, polypropylene imine, cyclodextrin, calixarene, etc.) are mentioned too, but to a smaller extent. Their syntheses, physicochemical properties and biological activities are given with many examples. Glycopeptide dendrimers can be used as inhibitors of cell surface protein-carbohydrate interactions, intervention with bacterial adhesion, for studying of recognition processes, diagnostics, imaging and contrast agents, mimetics, for complexation of different cationts, as site-specific molecular delivery systems, for therapeutic purposes, as immunodiagnostics and in drug design. Biomedical applications of glycopeptide dendrimers as drug and gene delivery systems are also given.
- MeSH
- antigeny chemie MeSH
- biopolymery chemie MeSH
- buněčná membrána metabolismus MeSH
- chemie farmaceutická metody MeSH
- dendrimery chemie MeSH
- financování organizované MeSH
- genomika metody MeSH
- glykomika metody MeSH
- glykopeptidy fyziologie chemie MeSH
- kalixareny chemie MeSH
- konformace proteinů MeSH
- lidé MeSH
- peptidy chemie MeSH
- proteomika metody MeSH
- sacharidy chemie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- přehledy MeSH
