Polymyxin B1 is a cationic lipopeptide that exhibits strong affinity for lipid bilayers through hydrophobic-electrostatic complementarity. Its cyclic and linear domains generate a rigid yet amphipathic scaffold. Researchers study its membrane-disruption mechanisms and binding thermodynamics. Applications include antimicrobial-peptide modeling, lipid-interaction studies, and sequence-activity profiling.
CAT No: R2569
CAS No:4135-11-9
Synonyms/Alias:4135-11-9;UNII-B35S89JSRU;B35S89JSRU;(6S)-N-[(2S)-4-amino-1-[[(2S,3R)-1-[[(2S)-4-amino-1-oxo-1-[[(3S,6S,9S,12S,15R,18S,21S)-6,9,18-tris(2-aminoethyl)-15-benzyl-3-[(1R)-1-hydroxyethyl]-12-(2-methylpropyl)-2,5,8,11,14,17,20-heptaoxo-1,4,7,10,13,16,19-heptazacyclotricos-21-yl]amino]butan-2-yl]amino]-3-hydroxy-1-oxobutan-2-yl]amino]-1-oxobutan-2-yl]-6-methyloctanamide;CHEMBL2397513;BRN 0505906;L-THREONINE, N2-(6-METHYL-1-OXOOCTYL)-L-2,4-DIAMINOBUTANOYL-L-THREONYL-L-2,4-DIAMINOBUTANOYL-L-2,4-DIAMINOBUTANOYL-L-2,4-DIAMINOBUTANOYL-D-PHENYLALANYL-L-LEUCYL-L-2,4-DIAMINOBUTANOYL-L-2,4-DIAMINOBUTANOYL-, CYCLIC (10->4)-PEPTIDE;N2-(6-METHYL-1-OXOOCTYL)-L-2,4-DIAMINOBUTANOYL-L-THREONYL-L-2,4-DIAMINOBUTANOYL-L-2,4-DIAMINOBUTANOYL-L-2,4-DIAMINOBUTANOYL-D-PHENYLALANYL-L-LEUCYL-L-2,4-DIAMINOBUTANOYL-L-2,4-DIAMINOBUTANOYL-L-THREONINE CYCLIC (10->4)-PEPTIDE;CHEBI:8309;DTXSID80858844;DTXCID1028441;SCHEMBL14241069;HY-A0248A;BDBM50548037;MS-32043;CS-0019929;(S)-N-((S)-4-amino-1-(((2S,3R)-1-(((S)-4-amino-1-oxo-1-(((3S,6S,9S,12S,15R,18S,21S)-6,9,18-tris(2-aminoethyl)-15-benzyl-3-((R)-1-hydroxyethyl)-12-isobutyl-2,5,8,11,14,17,20-heptaoxo-1,4,7,10,13,16,19-heptaazacyclotricosan-21-yl)amino)butan-2-yl)amino;
Polymyxin B1 is a cationic cyclic lipopeptide antibiotic produced by certain strains of Bacillus polymyxa. As a member of the polymyxin family, it is distinguished by its unique amphipathic structure, which allows it to interact specifically with the lipid A component of Gram-negative bacterial outer membranes. This compound is widely recognized for its potent bactericidal activity against multidrug-resistant Gram-negative pathogens, making it a valuable tool in microbiological and biochemical research. Its mechanism of action, involving disruption of membrane integrity, has positioned it as a reference molecule for studying membrane-targeting agents and bacterial resistance mechanisms.
Antimicrobial susceptibility testing: Polymyxin B1 serves as a benchmark compound in antimicrobial susceptibility assays designed to evaluate the resistance profiles of Gram-negative bacteria. Researchers utilize it to determine minimum inhibitory concentrations (MICs) and to compare the efficacy of novel antimicrobial agents. Its well-characterized mode of action provides a reliable control for validating experimental protocols and understanding bacterial response patterns under selective pressure.
Membrane permeability studies: Due to its affinity for lipopolysaccharides and its ability to perturb bacterial membranes, this lipopeptide is frequently employed in investigations of membrane permeability and integrity. Scientists exploit its interaction with lipid A to probe the structural and functional properties of bacterial outer membranes, facilitating the development of assays that assess barrier function, uptake of compounds, or membrane destabilization by experimental agents.
Mechanistic research on antibiotic resistance: Polymyxin B1 is instrumental in elucidating molecular mechanisms underlying resistance to cationic peptides. By exposing bacterial cultures to this compound, researchers can induce adaptive responses and characterize genetic or biochemical pathways that confer decreased susceptibility. These studies contribute to a deeper understanding of resistance evolution and inform the design of next-generation antimicrobials targeting similar pathways.
Endotoxin neutralization assays: The strong binding affinity of this peptide for the lipid A moiety of lipopolysaccharides enables its use in endotoxin neutralization experiments. In vitro systems often incorporate it to sequester and inactivate endotoxins, allowing scientists to dissect inflammatory responses or to validate the efficacy of endotoxin removal methods in laboratory reagents and bioprocessing applications.
Analytical reference standard: Owing to its well-defined chemical structure and biological activity, polymyxin B1 is employed as a reference standard in analytical chemistry workflows. Laboratories utilize it for the calibration of chromatographic methods, quality control of related lipopeptide preparations, and validation of detection techniques for antimicrobial residues in environmental or industrial samples. This ensures accuracy and consistency in quantitative and qualitative analyses involving polymyxin-class compounds.
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