1,721,012 research outputs found
New Developments in Heterocyclic Silyl Enol Ether Chemistry: Synthesis and Lewis Acid Mediated Reactions with Carbon Electrophiles of 2,5-bis(trimethylsiloxy)thiophene and 1-Methyl-2,5-bis(trimethylsiloxy)pyrrole
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Toxin-related antibodies with antimicrobial and antiviral activity
No full textAnti-idiotypic antibodies which recognise the idiotope of an antibody specific for a yeast killer toxin possess microbicidal activity. Fragments (e.g. decapeptides) of these anti-idiotypic antibodies, particularly those comprising CDR residues, also show microbicidal activity, as do peptides having 5 the same sequence but composed of D-amino acids, or including amino acid substitutions. Peptidomimetics of these microbicidal polypeptides are also provided. Antiviral activity is also seen
Mimotopes of the nicotinic receptor binding site selected by a combinatorial peptide library
No full textPeptide libraries allow selecting new molecules, defined as mimotopes, which are able to mimic the structural and functional features of a native protein. This technology can be applied for the development of new reagents, which can interfere with the action of specific ligands on their target receptors. In the present study we used a combinatorial library approach to produce synthetic peptides mimicking the snake neurotoxin binding site of nicotinic receptors. On the basis of amino acid sequence comparison of different alpha-bungarotoxin binding receptors, we designed a 14 amino acid combinatorial synthetic peptide library with five invariant, four partially variant, and five totally variant positions. Peptides were synthesized using SPOT synthesis on cellulose membranes, and binding sequences were selected using biotinylated alpha-bungarotoxin. Each variant position was systematically identified, and all possible combinations of the best reacting amino acids in each variant position were tested. The best reactive sequences were identified, produced in soluble form, and tested in BIACORE to compare their kinetic constants. We identified several different peptides that can inhibit the binding of alpha-bungarotoxin to both muscle and neuronal nicotinic receptors. Peptide mimotopes have a toxin-binding affinity that is considerably higher than peptides reproducing native receptor sequence
Structure and antigenic activity of rubella E1 glycoprotein synthetic peptides
No full textMinimal sequences of rubella E1 glycoprotein epitopes were previously identified as the tripeptide 250PER252 for the EP2 epitope, the tetrapeptide 260ADDP263 for the EP3 epitope, and the tripeptide 273EVW275 plus the octapeptide 278PVIGSQAR285 for the EP1 epitope. In order to establish for each epitope the shortest sequence that was able to give the maximum binding with human antirubella immunoglobulins, synthetic peptides with increasing number of residues flanking these essential parts of rubella E1 glycoprotein epitopes were synthesized and examined for their antigenic activity. Usually higher activity was observed with progressively longer homologues, whereas the additions of Pro‐271, Pro‐278 to 272GEVWVT277 peptide, and additions of Ala‐248 to 249TPERP253and 249TPERPR254, led to an abrupt decrease in binding. Taken together, our results indicated that the antigenic activity of the whole antigen could be dissected and reproduced using synthetic peptides of appropriate structure for each epitope
Bioactive peptides from libraries
No full textNew ligands for a variety of biological targets can be selected from biological or synthetic combinatorial peptide libraries. The use of different libraries to select novel peptides with potential therapeutic applications is reviewed. The possible combination of molecular diversity provided by combinatorial libraries and a rational approach derived from computational modeling is also considered. Advantages and disadvantages of different approaches are compared. Possible strategies to bypass loss of peptide bioactivity in the transition from ligand selection to in vivo use are discusse
Binding of HIV-1 gp120 to the nicotinic receptor
No full textWe previously described a significant sequence homology between HIV-1 gp120 and the functional sites responsible for the specific binding of snake curare-mimetic neurotoxins and rabies virus glycoprotein to the nicotinic acetylcholine receptor. Here we report findings about the existence of a mechanism of functional molecular mimicry which could enable the binding of HIV-1 gp120 to nicotinic acetylcholine receptors in muscle cells and neurons
A model of the rabies virus glycoprotein active site
No full textThe glycoprotein from the neurotropic rabies virus shows a significant homology with the alpha neurotoxin that binds to the nicotinic acetylcholine receptor. The crystal structure of the alpha neurotoxins suggests that the Arg 37 guanidinium group and the Asp 31 side-chain carboxylate of the erabutoxin have stereochemical features resembling those of acetylcholine. Conformational studies on the Asn194-Ser195-Arg196-Gly197 tetrapeptide, an essential part of the binding site of the rabies virus glycoprotein, indicate that the side chains of Asn and Arg could also mimic the acetylcholine structure. This observation is consistent with the recently proposed mechanism of the viral infection
High performance liquid chromatography immunoaffinity purification of antibodies and antibody fragments
No full textA rapid antibody purification method is described which combines high performance liquid chromatography (HPLC) resolution with affinity chromatography specificity. The antigen used as immobilized ligand is bound to the HPLC column matrix by reacting the amino groups of the protein with the active epoxy groups of the latter. Once the reaction has finished, the unreacted groups of the column are saturated with an appropriate scavenger. Unrelated proteins are then washed out and the specific antibodies recovered by lowering the pH of the elution buffer
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