Complete thermodynamic characterization of the multiple protonation equilibria of the aminoglycoside antibiotic paromomycin:: A calorimetric and natural abundance 15N NMR study
Complete thermodynamic characterization of the multiple protonation equilibria of the aminoglycoside antibiotic paromomycin:: A calorimetric and natural abundance 15N NMR study
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DOI：
10.1529/biophysj.105.075028
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发表时间：
2006-02-01
影响因子：
3.4
通讯作者：
Pilch, DS
中科院分区：
文献类型：
--
作者：
Barbieri, CM;Pilch, DS
氨基糖苷类抗生素与广泛的大分子靶点的结合与代表这类药物的一个或多个氨基的质子化偶联。确定如何以及在何种程度上影响这种连接的氨基糖苷类大分子结合反应的能量需要详细了解与氨基糖苷类氨基的质子化平衡相关的热力学。在认识到这一点，量热和NMR为基础的方法，用于获得必要的热力学信息，提出了使用巴龙霉素作为模型氨基糖苷。温度和pH依赖性15 NNMR研究提供了5个巴龙霉素氨基的pKa（a）值，以及这些pKa值的温度依赖性。这些研究还表明，观察到的与巴龙霉素游离碱形式相关的pKa值在幅度上低于与药物硫酸盐形式相关的相应值。pKa的这种差异是由于在N-15 NMR研究中使用的高药物浓度（>= 812 mM）下药物与硫酸根抗衡离子的相互作用。在药物浓度下进行的等温滴定量热法研究
The binding of aminoglycoside antibiotics to a broad range of macromolecular targets is coupled to protonation of one or more of the amino groups that typify this class of drugs. Determining how and to what extent this linkage influences the energetics of the aminoglycoside-macromolecule binding reaction requires a detailed understanding of the thermodynamics associated with the protonation equilibria of the aminoglycoside amino groups. In recognition of this need, a calorimetric- and NMR-based approach for obtaining the requisite thermodynamic information is presented using paromomycin as the model aminoglycoside. Temperature- and pH-dependent 15 NNMR studies provide pK(a) values for the five paromomycin amino groups, as well as the temperature dependence of these pKa values. These studies also indicate that the observed pKa values associated with the free base form of paromomycin are lower in magnitude than the corresponding values associated with the sulfate salt form of the drug. This difference in pKa is due to drug interactions with the sulfate counterions at the high drug concentrations (>= 812 mM) used in the N-15 NMR studies. Isothermal titration calorimetry studies conducted at drug concentrations