The interaction mechanism between lipopeptide (daptomycin) and polyamidoamine (PAMAM) dendrimers

The interaction mechanism of lipopeptide antibiotic daptomycin and polyamidoamine (PAMAM) dendrimers was studied using fluorescence spectroscopy. The fluorescence changes observed are associated with daptomycin–dendrimer interactions. The binding isotherms were constructed by plotting the fluorescen...

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Bibliographic Details
Published in:Journal of peptide science 2015-04, Vol.21 (4), p.312-319
Main Authors: Chanvorachote, Boontarika, Qiu, Jiang, Muangsiri, Walaisiri, Nimmannit, Ubonthip, Kirsch, Lee E.
Format: Article
Language:English
Subjects:
Anti-Bacterial Agents - chemistry
daptomycin
Daptomycin - chemistry
Dendrimers - chemistry
fluorescence spectroscopy
Hydrogen-Ion Concentration
lipopeptide
peptide delivery
Peptides
polyamidoamine (PAMAM) dendrimers
Polyamines - chemistry
polymeric drug delivery
Spectrometry, Fluorescence
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Summary:The interaction mechanism of lipopeptide antibiotic daptomycin and polyamidoamine (PAMAM) dendrimers was studied using fluorescence spectroscopy. The fluorescence changes observed are associated with daptomycin–dendrimer interactions. The binding isotherms were constructed by plotting the fluorescence difference at 460 nm from kynurenine (Kyn‐13) of daptomycin in the presence and absence of dendrimer. A one‐site and two‐site binding model were quantitatively generated to estimate binding capacity and affinity constants from the isotherms. The shape of the binding isotherm and the dependence of the estimated capacity constants on dendrimer sizes and solvent pH values provide meaningful insight into the mechanism of interactions. A one‐site binding model adequately describes the binding isotherm obtained under a variety of experimental conditions with dendrimers of various sizes in the optimal binding pH region 3.5 to 4.5. Comparing the pH‐dependent binding capacity with the ionization profiles of daptomycin and dendrimer, the ionized aspartic acid residue (Asp‐9) of daptomycin primarily interact with PAMAM cationic surface amine. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd. Daptomycin and polyamidoamine (PAMAM) dendrimer interactions as a function of dendrimer size and pH were studied using fluorescence spectroscopy. One‐site binding models were adequate to quantify the interactions of daptomycin and PAMAM 3 and 5 whereas a two‐site model accounted for interactions with PAMAM 6. Comparison of the pH‐dependent binding capacity with daptomycin and dendrimer ionization profiles suggested that electrostatic interactions between the ionized Asp‐9 daptomycin residue and PAMAM cationic surface amines were the primary binding mechanism.
ISSN:1075-2617
1099-1387
DOI:10.1002/psc.2752