Table 1.
Carbon position labeled | 13C-Carbon source: 1,3-Glycerol only | 13C-Carbon source: 1,3-Glycerol and Formate |
---|---|---|
Purinea | ||
Ade C2 | 0.88 ± 0.04 | 0.82 ± 0.13 |
C8 | 0.92 ± 0.07 | 0.81 ± 0.13b |
Pyrimidinea | ||
C5 | 0.88 ± 0.04 | 0.92 ± 0.03 |
C6 | <0.05 | 0.22 ± 0.02 |
Ribose | ||
C1′a | 0.58 ± 0.08 | 0.47 ± 0.11 |
C2′b | 0.50 ± 0.04 | 0.57 ± 0.09 |
C3′b | 0.93 ± 0.01 | 0.77 ± 0.07 |
C4′b | <0.02 | <0.02 |
C5′c | 0.94 ± 0.03 | 0.85 ± 0.06 |
aThe percentage label is calculated as an average of three methods: (i) the ratio of the sum of the intensities of satellite peaks to the sum of the intensities of the satellite and center peaks using the 2-bond 15N HSQC without 13C decoupling during acquisition (Dayie and Thakur 2010); (ii) the ratio of the sum of the intensities of satellite peaks to the sum of the intensities of the satellite and center peaks using the 1D 1H experiment without 13C decoupling during acquisition and (iii) using the fractional enrichment (Frac_Ei) method of Lundström et al. (2007) as described in the text. We find that direct 1D and 2D methods (i and ii) give consistently slightly higher values than the fractional enrichment method (iii)
bThe percentage label (Plabel) is calculated as in (a) but this time with only method (iii)
cThe percentage label (Plabel) is calculated as in (a) but this time with only methods (ii) and (iii)