. 2020 Aug 11;5(33):21094–21103. doi: 10.1021/acsomega.0c02744

Table 4. pK_a Values of Individual Nitrogen Atoms of Sisomicin Determined Using ¹H, ¹³C, and ¹⁵N HMBC NMR Spectroscopy in This Work and Then Compared With the Published Data, as Indicated.

	individual nitrogen atoms pK_a
method	N-1	N-3	N-2′	N-6′	N-3″
¹H NMR^a	7.34	6.11	7.93	9.45	8.63
¹H NMR^b	7.42	6.18	7.98	9.35^c	8.51
¹³C NMR^b	7.45	6.25	7.99	9.28	8.45
¹⁵N HMBC NMR^b	7.41	6.24	8.05	9.29	8.55

pK_a values of individual nitrogen atoms of sisomicin determined using ¹H NMR spectroscopy in D₂O relative to TSP at 25 °C.¹⁷

This work.

The pK_a value of N-6′ of sisomicin determined using ¹H NMR spectroscopy (in this work) is the average pK_a of the values of N-6′ obtained using ¹H NMR spectroscopic data for 6′a (9.35) and 6′b (9.35), which gave the same value.

Table 4. pKa Values of Individual Nitrogen Atoms of Sisomicin Determined Using 1H, 13C, and 15N HMBC NMR Spectroscopy in This Work and Then Compared With the Published Data, as Indicated.

Table 4. pK_a Values of Individual Nitrogen Atoms of Sisomicin Determined Using ¹H, ¹³C, and ¹⁵N HMBC NMR Spectroscopy in This Work and Then Compared With the Published Data, as Indicated.