Chemistry Reference
In-Depth Information
150
duplex (
1.3
)
T5, T16
155
160
150
duplex (
2.3
)
T6, T16
155
160
150
duplex (
2.4
)
T6, T15
155
160
11.0
10.5
10.0
9.5
1
H (ppm)
Figure 16.5
1
H-
15
N HSQC spectra of duplexes (
1
·
3
), (
2
·
3
) and (
2
·
4
). By using these three
spectra, we can assign each cross peak. For example, in the top and middle panels, the N-H
cross peak of the T16 residue should be observed. Therefore, the cross peak at 10.2 ppm (
1
H),
154.4 ppm (
15
N) is the N-H cross peak of T16. Similarly, the cross peak at 10.3 ppm (
1
H),
153.9 ppm (
15
N) is that of T6. Finally, the cross peaks at 10.9 ppm (
1
H), 155.1 ppm (
15
N) and at
10.7 ppm (
1
H), 155.8 ppm (
15
N) are those of T5 and T15, respectively. (Reprinted with permission
from
J. Am. Chem. Soc
., 2007,
129
, 244-245. Copyright 2007 American Chemical Society.)
16.5 Relationship Between
15
N Chemical Shifts and Chemical Bonds
We investigated theoretical aspects of chemical shifts of N3 resonance at the Hg
II
binding site to understand chemical reasons why the N3 resonances shifted toward
such a low fi eld upon Hg
II
binding. From the defi nition of a chemical shift, the
