Evaluation of lipopeptide (daptomycin) aggregation using fluorescence, light scattering, and nuclear magnetic resonance spectroscopy.
The aggregation behavior and critical aggregation concentration (CAC) values of daptomycin in aqueous solutions were evaluated under the external factors of pH, temperature, daptomycin concentration, and calcium ions concentration by using the complementary characterization techniques, fluorescence, dynamic and static light scattering, and nuclear magnetic resonance (NMR) spectroscopy. On the basis of the intrinsic fluorescence resonance energy transfer of daptomycin, the CAC values were identified by an upward inflection of the fluorescence emission from Kyn-13 at 460 nm. The pH-dependent CAC values were determined to be 0.14 mM at pH 3.0, 0.12 mM at pH 4.0, and 0.20 mM at pH 2.5 and 5.0. The CAC values obtained by fluorescence spectroscopy were confirmed by dynamic light scattering and NMR spectroscopy.
Division of Pharmaceutics, College of Pharmacy, University of Iowa, Iowa City, Iowa, 52242.
Jiang
J
Qiu
Lee E
LE
Kirsch
D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000378:metabolism; D020013:Calcium Signaling; D017576:Daptomycin / Q000737:chemistry* / Q000378:metabolism; D004355:Drug Stability; D031541:Fluorescence Resonance Energy Transfer; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007476:Ionophores / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D007736:Kynurenic Acid / Q000737:chemistry; D007737:Kynurenine / Q000737:chemistry / Q000378:metabolism; D009391:Nephelometry and Turbidimetry; D019906:Nuclear Magnetic Resonance, Biomolecular; D009994:Osmolar Concentration; D010316:Particle Size; D055550:Protein Stability; D012995:Solubility; D013056:Spectrophotometry, Ultraviolet; D014364:Tryptophan / Q000737:chemistry
D000900:Anti-Bacterial Agents; D007476:Ionophores; D007737:Kynurenine; D014364:Tryptophan; D007736:Kynurenic Acid; D017576:Daptomycin
NMR spectroscopy; analytical chemistry; daptomycin; dynamic light scattering; fluorescence spectroscopy; lipopeptide antibiotic; peptide aggregation; spectroscopy; static light scattering; zwitterion