306
N
N
N
N
NH 2
O
H
OH
H
H
H
H
O
P
O
O
–
O
P
–
O
O
–
O
N
N
N
N
NH 2
O
H
O
H
H
H
H
O
P
–
O
O
N
N
N
N
NH 2
O
H
OH
H
H
H
H
O
P
O
O
–
O
P
O
O
–
O
P
–
O
O
–
O
N
N
N
N
NH 2
O
H
OH
H
H
H
H
O
P
O
–
O
O
P
O
–
O
O
N
HO
HO
OH
N
HN
N
O
O
N
N
N
N
NH 2
O
H
OH
H
H
H
H
O
P
–
O
O
–
O
N
N
N
N
NH 2
O
O
O
H
H
H
H
HO
P
O
–
O
-7.3
-5.6
-20.4
-11.0
1.6
-21.8
4.0
-9.7
-10.8 and -11.3
(pH 7.8,
5 mM MgCl 2 )
(pH 7.8,
5 mM MgCl 2 )
Heteronuclear NMR Spectroscopy
6