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Design, synthesis, and evaluation of a new fluorescent probe for measuring polymyxin-lipopolysaccharide binding interactions.

ABSTRACT: Fluorescence assays employing semisynthetic or commercial dansyl-polymyxin B have been widely employed to assess the affinity of polycations, including polymyxins, for bacterial cells and lipopolysaccharide (LPS). The five primary ?-amines on diaminobutyric acid residues of polymyxin B are potentially derivatized with dansyl-chloride. Mass spectrometric analysis of the commercial product revealed a complex mixture of di- or tetra-dansyl-substituted polymyxin B. We synthesized a mono-substituted fluorescent derivative, dansyl[Lys]¹polymyxin B?. The affinity of polymyxin for purified gram-negative LPS and whole bacterial cells was investigated. The affinity of dansyl[Lys]¹polymyxin B? for LPS was comparable to polymyxin B and colistin, and considerably greater (K(d)<1 ?M) than for whole cells (K(d)?6-12?M). Isothermal titration calorimetric studies demonstrated exothermic enthalpically driven binding between both polymyxin B and dansyl[Lys]¹polymyxin B? to LPS, attributed to electrostatic interactions. The hydrophobic dansyl moiety imparted a greater entropic contribution to the dansyl[Lys]¹polymyxin B?-LPS reaction. Molecular modeling revealed a loss of electrostatic contact within the dansyl[Lys]¹polymyxin B?-LPS complex due to steric hindrance from the dansyl[Lys]¹ fluorophore; this corresponded with diminished antibacterial activity (MIC?16?g/mL). Dansyl[Lys]¹polymyxin B? may prove useful as a screening tool for drug development.

SUBMITTER: Soon RL

PROVIDER: S-EPMC3106281 | biostudies-literature | 2011 Feb

REPOSITORIES: biostudies-literature

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Design, synthesis, and evaluation of a new fluorescent probe for measuring polymyxin-lipopolysaccharide binding interactions.

Soon Rachel L RL Velkov Tony T Chiu Francis F Thompson Philip E PE Kancharla Rashmi R Roberts Kade K Larson Ian I Nation Roger L RL Li Jian J

Analytical biochemistry 20101102 2

Fluorescence assays employing semisynthetic or commercial dansyl-polymyxin B have been widely employed to assess the affinity of polycations, including polymyxins, for bacterial cells and lipopolysaccharide (LPS). The five primary γ-amines on diaminobutyric acid residues of polymyxin B are potentially derivatized with dansyl-chloride. Mass spectrometric analysis of the commercial product revealed a complex mixture of di- or tetra-dansyl-substituted polymyxin B. We synthesized a mono-substituted ...[more]

PMID: 21050838

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Dataset Information

Design, synthesis, and evaluation of a new fluorescent probe for measuring polymyxin-lipopolysaccharide binding interactions.

Publications

Design, synthesis, and evaluation of a new fluorescent probe for measuring polymyxin-lipopolysaccharide binding interactions.

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