Table 6. Average pKa Values of Individual Nitrogen Atoms of the Indicated Aminoglycosides Using 1H, 13C, and 1H-15N HMBC NMR Spectroscopies.
| individual
nitrogen atoms |
||||||
|---|---|---|---|---|---|---|
| aminoglycoside | N-1 | N-3 | N-2′ | N-6′ | N-2‴ | N-6‴ |
| 2-deoxystreptamine (n = 3) | 9.26 | 7.00 | ||||
| 1H | 9.25 ± 0.05 | 6.97 ± 0.04 | ||||
| 13C | 9.35 ± 0.10 | 7.03 ± 0.05 | ||||
| 15N | 9.20 ± 0.05 | 7.01 ± 0.05 | ||||
| neamine (n = 2) | 7.60 | 6.51 | 7.11 | 8.31 | ||
| 1H | 7.62 ± 0.03 | 6.50 ± 0.04 | 7.10 ± 0.05 | 8.34 ± 0.05 | ||
| 13C | 7.60 ± 0.05 | 6.55 ± 0.05 | 7.05 ± 0.05 | 8.25 ± 0.05 | ||
| 15N | 7.60 ± 0.05 | 6.50 ± 0.05 | 7.20 ± 0.10 | 8.35 ± 0.05 | ||
| neomycin (n = 2) | 8.08 | 6.86 | 7.98 | 8.65 | 8.03 | 8.76 |
| 1H | 8.10 ± 0.07 | 6.90 ± 0.02 | 8.00 ± 0.05 | 8.67 ± 0.05 | 8.05 ± 0.05 | 8.73 ± 0.05 |
| 13C | 8.00 ± 0.05 | 6.90 ± 0.05 | 8.00 ± 0.05 | 8.70 ± 0.04 | 8.15 ± 0.06 | 8.86 ± 0.10 |
| 15N | 8.15 ± 0.10 | 6.80 ± 0.05 | 7.95 ± 0.07 | 8.60 ± 0.05 | 7.90 ± 0.10 | 8.71 ± 0.07 |
| paromomycin | 8.11 | 6.50 | 8.06 | 8.10 | 9.08 | |
| 1H | 8.25 | 6.45 | 8.10 | 8.20 | 9.15 | |
| 13C | 8.10 | 6.55 | 8.00 | 8.11 | 9.00 | |
| 15N | 8.00 | 6.50 | 8.10 | 8.00 | 9.10 | |
| streptomycin | 13.06 | 12.06 | 8.16 | |||
| 1H | 13.20 | 12.10 | 8.38 | |||
| 13C | 13.02 | 11.95 | 8.11 | |||
| 15N | 12.97 | 12.15 | 8.01 | |||