Individual pKa Values of Tobramycin, Kanamycin B, Amikacin, Sisomicin, and Netilmicin Determined by Multinuclear NMR Spectroscopy

NMR spectroscopy is a powerful technique for separating and measuring each distinct pK(a) value of the amino groups around aminoglycoside antibiotics. Unambiguous assignments were made for each individual amine substituent on 2-deoxystreptamine, tobramycin, kanamycin B, amikacin, sisomicin, and netilmicin using variations in the NMR spectroscopic chemical shift (delta) with H-1, C-13, and N-15 HMBC; the individual pK(a) values of netilmicin are reported for the first time.