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Biochemical and Biophysical Research... Jan 2017B cell lymphoma 6 (BCL6) is a transcriptional repressor that interacts with its corepressors BcoR and SMRT. Since this protein-protein interaction (PPI) induces...
B cell lymphoma 6 (BCL6) is a transcriptional repressor that interacts with its corepressors BcoR and SMRT. Since this protein-protein interaction (PPI) induces activation and differentiation of B lymphocytes, BCL6 has been an attractive drug target for potential autoimmune disease treatments. Here we report a novel BCL6 inhibitory peptide, F1324 (Ac-LWYTDIRMSWRVP-OH), which we discovered using phage display technology; we also discuss this peptide's structure-activity relationship (SAR). For BCL6(5-129) binding, K and IC values of F1324 were 0.57 nM and 1 nM according to the results of an SPR analysis and cell-free ELISA assay, respectively. In contrast, BcoR(Arg498-514Pro) and SMRT(Leu1422-Arg1438) exhibited relatively weak micromole-order binding to BCL6. Furthermore, Fusion protein AcGFP-F1324 transiently expressed in HEK293T cells inhibited intracellular PPI in cell-based M2H assay. By examination of the truncation and fragmentation of F1324, the C-terminal sequence WRVP, which is similar to the BcoR(509-512) sequence WVVP, was identified as being critical for BCL6 binding. In addition, subsequent single-crystal X-ray diffraction analysis of F1324/BCL6(5-129) complex revealed that the high affinity of F1324 was caused by effective interaction of its side chains while its main chain structure was similar to that of BcoR(Arg498-514Pro). To our knowledge, F1324 is the strongest BCL6-binding peptide yet reported.
Topics: Binding Sites; Enzyme Activation; Enzyme Inhibitors; Peptides; Protein Binding; Proto-Oncogene Proteins c-bcl-6; Structure-Activity Relationship
PubMed: 27856253
DOI: 10.1016/j.bbrc.2016.11.060 -
Chemistry (Weinheim An Der Bergstrasse,... Oct 2015Recent structural studies on libraries of cyclic hexapeptides led to the identification of common backbone conformations that may be instrumental to the oral...
Recent structural studies on libraries of cyclic hexapeptides led to the identification of common backbone conformations that may be instrumental to the oral availability of peptides. Furthermore, the observation of differential Caco-2 permeabilities of enantiomeric pairs of some of these peptides strongly supports the concept of conformational specificity driven uptake and also suggests a pivotal role of carrier-mediated pathways for peptide transport, especially for scaffolds of polar nature. This work presents investigations on the Caco-2 and PAMPA permeability profiles of 13 selected N-methylated cyclic pentaalanine peptides derived from the basic cyclo(-D-Ala-Ala4 -) template. These molecules generally showed moderate to low transport in intestinal epithelia with a few of them exhibiting a Caco-2 permeability equal to or slightly higher than that of mannitol, a marker for paracellular permeability. We identified that the majority of the permeable cyclic penta- and hexapeptides possess an N-methylated cis-peptide bond, a structural feature that is also present in the orally available peptides cyclosporine A and the tri-N-methylated analogue of the Veber-Hirschmann peptide. Based on these observations it appears that the presence of N-methylated cis-peptide bonds at certain locations may promote the intestinal permeability of peptides through a suitable conformational preorganization.
Topics: Biological Transport; Caco-2 Cells; Cell Membrane Permeability; Humans; Intestinal Absorption; Intestinal Mucosa; Intestines; Methylation; Peptides; Peptides, Cyclic; Permeability; Stereoisomerism
PubMed: 26337831
DOI: 10.1002/chem.201501600 -
Archives of Histology and Cytology 1989The authors present an overview of the main amphibian peptide families mainly derived from the skin and mostly discovered by Erspamer and his associates. The studies of... (Review)
Review
The authors present an overview of the main amphibian peptide families mainly derived from the skin and mostly discovered by Erspamer and his associates. The studies of the peptides do not only promote the understanding of their chemical, metabolical and physiological features of those molecules in amphibians, but also contribute to progress in our knowledge of the corresponding mammalian counterparts. Particular reference is made on sauvagine, tachykinin, bombesin and dermorphin families, offering new data mostly from personal contributions to this field.
Topics: Amphibians; Animals; Brain Chemistry; Digestive System; Peptides; Skin
PubMed: 2510789
DOI: 10.1679/aohc.52.suppl_317 -
Diabetes Jan 2012Glucagon is believed to be one of the most important peptides for upregulating blood glucose levels. However, homozygous glucagon-green fluorescent protein (gfp)...
Glucagon is believed to be one of the most important peptides for upregulating blood glucose levels. However, homozygous glucagon-green fluorescent protein (gfp) knock-in mice (Gcg(gfp/gfp): GCGKO) are normoglycemic despite the absence of proglucagon-derived peptides, including glucagon. To characterize metabolism in the GCGKO mice, we analyzed gene expression and metabolome in the liver. The expression of genes encoding rate-limiting enzymes for gluconeogenesis was only marginally altered. On the other hand, genes encoding enzymes involved in conversion of amino acids to metabolites available for the tricarboxylic acid cycle and/or gluconeogenesis showed lower expression in the GCGKO liver. The expression of genes involved in the metabolism of fatty acids and nicotinamide was also altered. Concentrations of the metabolites in the GCGKO liver were altered in manners concordant with alteration in the gene expression patterns, and the plasma concentrations of amino acids were elevated in the GCGKO mice. The insulin concentration in serum and phosphorylation of Akt protein kinase in liver were reduced in GCGKO mice. These results indicated that proglucagon-derived peptides should play important roles in regulating various metabolic pathways, especially that of amino acids. Serum insulin concentration is lowered to compensate the impacts of absent proglucagon-derived peptide on glucose metabolism. On the other hand, impacts on other metabolic pathways are only partially compensated by reduced insulin action.
Topics: Amino Acids; Animals; Gene Expression Regulation, Enzymologic; Green Fluorescent Proteins; Lipid Metabolism; Liver; Male; Metabolic Diseases; Metabolic Networks and Pathways; Mice; Mice, Inbred C57BL; Mice, Knockout; Models, Biological; Peptide Fragments; Proglucagon; Up-Regulation
PubMed: 22187375
DOI: 10.2337/db11-0739 -
Biochemistry Jan 2019
Topics: High-Throughput Screening Assays; Peptide Biosynthesis, Nucleic Acid-Independent; Peptide Synthases; Peptides; Peptides, Cyclic; Protein Biosynthesis; Ribosomes
PubMed: 30335368
DOI: 10.1021/acs.biochem.8b00930 -
Bioorganic & Medicinal Chemistry Letters Oct 2017Neuromedin U (NMU) mediates various physiological functions via NMUR1 and NMUR2 receptors. NMUR2 has been considered a promising treatment option for diabetes and...
Neuromedin U (NMU) mediates various physiological functions via NMUR1 and NMUR2 receptors. NMUR2 has been considered a promising treatment option for diabetes and obesity. Although NMU-8, a shorter peptide, has potent agonist activity for both receptors, it is metabolically unstable. Therefore, NMU-8 analogs modified with long-chain alkyl moieties via a linker were synthesized. An octadecanoyl analog (17) with amino acid substitutions [αMePhe, Nle, and Arg(Me)] and a linker [Tra-γGlu-PEG(2)] dramatically increased NMUR2 selectivity, with retention of high agonist activity. Subcutaneous administration of 17 induced anorectic activity in C57BL/6J mice. Owing to its high metabolic stability, 17 would be useful in clarifying the physiological role and therapeutic application of NMU.
Topics: Alkylation; Amino Acid Sequence; Animals; Appetite Depressants; Eating; Humans; Male; Mice; Mice, Inbred C57BL; Peptides; Receptors, Neurotransmitter; Structure-Activity Relationship
PubMed: 28935264
DOI: 10.1016/j.bmcl.2017.09.019 -
Analytica Chimica Acta May 2019We have developed a rapid and sensitive universal peptide-based time-resolved luminescence assay for detection of enzymatic post-translational modifications (PTMs). PTMs...
We have developed a rapid and sensitive universal peptide-based time-resolved luminescence assay for detection of enzymatic post-translational modifications (PTMs). PTMs play essential roles in intracellular signaling and cell regulation, thus providing functional protein diversity in cell. Due this, impaired PTM patterns have been linked to multiple disease states. Clear link between PTMs and pathological conditions have also driven assay development further, but still today most of the methodologies are based on single-specificity or group-specific PTM-recognition. We have previously introduced leuzine-zipper based peptide-break technology as a viable option for universal PTM detection. Here, we introduce peptide-break technology utilizing single-label homogeneous quenching resonance energy transfer (QRET) and charge-based peptide-peptide interaction. We demonstrate the functionality of the new assay concept in phosphorylation, deacetylation, and citrullination. In a comparable study between previously introduced leucine-zipper and the novel charge-based approach, we found equal PTM detection performance and sensitivity, but the peptide design for new targets is simplified with the charged peptides. The new concept allows the use of short <20 amino acid peptides without limitations rising from the leucine-zipper coiled-coil structure. Introduced methodology enables wash-free PTM detection in a 384-well plate format, using low nanomolar enzyme concentrations. Potentially, the peptide-break technique using charged peptides may be applicable for natural peptide sequences directly obtained from the target protein.
Topics: Acetylation; Amino Acid Sequence; Citrullination; Europium; Luminescent Measurements; Peptides; Protein Processing, Post-Translational
PubMed: 30782363
DOI: 10.1016/j.aca.2018.12.041 -
Nature Communications May 2024Life continuously transduces energy to perform critical functions using energy stored in reactive molecules like ATP or NADH. ATP dynamically phosphorylates active sites...
Life continuously transduces energy to perform critical functions using energy stored in reactive molecules like ATP or NADH. ATP dynamically phosphorylates active sites on proteins and thereby regulates their function. Inspired by such machinery, regulating supramolecular functions using energy stored in reactive molecules has gained traction. Enzyme-free, synthetic systems that use dynamic phosphorylation to regulate supramolecular processes have not yet been reported, to our knowledge. Here, we show an enzyme-free reaction cycle that consumes the phosphorylating agent monoamidophosphate by transiently phosphorylating histidine and histidine-containing peptides. The phosphorylated species are labile and deactivate through hydrolysis. The cycle exhibits versatility and tunability, allowing for the dynamic phosphorylation of multiple precursors with a tunable half-life. Notably, we show the resulting phosphorylated products can regulate the peptide's phase separation, leading to active droplets that require the continuous conversion of fuel to sustain. The reaction cycle will be valuable as a model for biological phosphorylation but can also offer insights into protocell formation.
Topics: Phosphorylation; Peptides; Histidine; Adenosine Triphosphate; Hydrolysis
PubMed: 38760374
DOI: 10.1038/s41467-024-48571-z -
Nature Chemical Biology Jan 2024Macrocyclic peptides represent promising scaffolds for chemical tools and potential therapeutics. Synthetic methods for peptide macrocyclization are often hampered by...
Macrocyclic peptides represent promising scaffolds for chemical tools and potential therapeutics. Synthetic methods for peptide macrocyclization are often hampered by C-terminal epimerization and oligomerization, leading to difficult scalability. While chemical strategies to circumvent this issue exist, they often require specific amino acids to be present in the peptide sequence. Herein, we report the characterization of Ulm16, a peptide cyclase belonging to the penicillin-binding protein-type class of thioesterases that catalyze head-to-tail macrolactamization of nonribosmal peptides. Ulm16 efficiently cyclizes various nonnative peptides ranging from 4 to 6 amino acids with catalytic efficiencies of up to 3 × 10 M s. Unlike many previously described homologs, Ulm16 tolerates a variety of C- and N-terminal amino acids. The crystal structure of Ulm16, along with modeling of its substrates and site-directed mutagenesis, allows for rationalization of this wide substrate scope. Overall, Ulm16 represents a promising tool for the biocatalytic production of macrocyclic peptides.
Topics: Penicillin-Binding Proteins; Cyclization; Peptides; Biocatalysis; Amino Acids; Peptides, Cyclic
PubMed: 38062262
DOI: 10.1038/s41589-023-01495-z -
Pharmaceutical Research Jul 2015For long-effective peptide formulation based on poly(D,L-lactic-co-glycolic acid) (PLGA) microspheres, acylation often leads to peptide instability during its release...
PURPOSE
For long-effective peptide formulation based on poly(D,L-lactic-co-glycolic acid) (PLGA) microspheres, acylation often leads to peptide instability during its release and reduced drug efficacy. Among the reported solving strategies, adding dication such as Ca(2+) and Mn(2+) in the formulation was the most convenient method for inhibiting basic peptide acylation. However, the strategies for the acidic peptide still remain unexplored, possibly due to the peptide's changeable charge state in acid environment within degraded PLGA microspheres. Moreover, the previous studies mainly focusing on the macroscopical adsorption of peptide to PLGA cannot demonstrate the inhibition mechanism.
METHODS
Acylation inhibition for acidic peptide (exenatide) by dications (Ca(2+), Mn(2+) and Zn(2+)) was studied for the first time, and Quartz Crystal Microbalance with Dissipation (QCM-D) was innovatively employed to analyze microcosmic mechanism of the inhibition.
RESULTS
These dications played different roles in acylation inhibition of acidic peptide. The effects of dications on acylation outside or inside PLGA microspheres indicated that Ca(2+) did not work, Mn(2+) played a weak role, and Zn(2+) possessed the greatest inhibition.
CONCLUSIONS
Zn(2+) was the most effective dication for the acylation inhibition because of the complex formation and its steric-hindrance effect, which was a new function for this dication.
Topics: Acylation; Cations, Divalent; Chemistry, Pharmaceutical; Drug Carriers; Drug Compounding; Drug Liberation; Drug Stability; Excipients; Exenatide; Lactic Acid; Microspheres; Peptides; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Solubility; Venoms
PubMed: 25585955
DOI: 10.1007/s11095-015-1622-5