O
H
OP3
P
P
O
H
OP1
O
OP2
C4'
O
O4'
C3'(S)
O
O3'
C2'(R)
C1'(R)
N
N9
C8
N
N7
C5
C6
O
O6
N
H
N1
C2
N
H
2
N2
N
N3
C4
O
H
O2'
N
N10
C14
N
H
2
N15
C11
C12
N
+
N13
P
P34
O
OP4
O
O33
C32(S)
C28(R)
O
H
O29
C31
O
O30
C27(R)
N
N26
C22
N
N21
C19
N
H
2
N20
N
H
N18
C17
O
O16
C23
N
N24
C25