Basicity of the Amino Groups of the Aminoglycoside Amikacin Using Capillary Electrophoresis and Coupled CE−MS−MS Techniques

• Published in: Analytical chemistry (Washington) Vol. 73; no. 16; pp. 4028 - 4036
• Main Authors: Kane, Ravi S, Glink, Peter T, Chapman, Robert G, McDonald, J. Cooper, Jensen, Pamela K, Gao, Hongying, Paša-Tolić, Ljiljana, Smith, Richard D, Whitesides, George M
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15-08-2001
• Subjects: Acetylation; Amikacin - chemistry; Amines - chemistry; Amino acids; Anti-Bacterial Agents - chemistry; Biological and medical sciences; Carbohydrate Conformation; Carbohydrate Sequence; Chemical bonds; Chemistry; Electrophoresis, Capillary - methods; General pharmacology; Hydrogen-Ion Concentration; Mass Spectrometry - methods; Medical sciences; Molecular Sequence Data; Pharmacology. Drug treatments; Physicochemical properties. Structure-activity relationships; Proteins; Ribonucleic acid; RNA; Spectroscopy, Fourier Transform Infrared; Acidity constant; Antibiotic; Capillary electrophoresis; Aminoglycoside; Mass spectrometry MS/MS; Electrostatic interaction; Molecular interaction; Basicity constant; Chemical properties; Antibacterial agent; Experimental study; Functional group
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac010173m

This paper describes the use of capillary electrophoresis (CE), and coupled CE and mass spectrometric techniques, to measure the values of the pK a of the amino groups of the aminoglycoside antibiotic amikacin and of its acetylated derivatives. These values of pK a (8.4, 6.7, 9.7, 8.4) were determined by measuring the electrophoretic mobilities of the molecules as a function of pH; they are within 0.7 unit of certain values reported in the literature (by 13C and 15N NMR spectroscopies) but resolved ambiguities left by these earlier studies. The range of values of pK a of amino groups also indicates the complex dependence of the acidity of a functional group (and thus the extent of ionization at a specified value of pH) on the molecular environment of that group.