BIOINORGANIC CHEMISTRY A Short Course Second Edition

52 BIOCHEMISTRY FUNDAMENTALS

Figure 2.16 Orientations found in DNA helices. [Adapted with permission from
Figure 2.11 of reference 14 (copyright 1984, Springer - Verlag) and Figure 1.22 A, B, C
of reference 15 (copyright 1997, Wiley - VCH).]

C 5 ' O 3 '

O4'

NH

N

N

O

N NH 2

O

OH H

H H

H H

HO

HN

N

N

O

H 2 N N

O

OH H

H H

H H

HO

O 5 '

H5'2

'O (^5) O4'
O4'
O 5 '
C 5 '
O 3 '
anti-deoxyguanosine
anti-dG
syn-deoxyguanosine
syn-dG
anti-cytidine, thymidine, uridine syn-cytidine, thymidine, uridine
C3' C 2 '
BASE
H5'1 γ
Definition of torsion angles about the C4'-C5' bond
looking in the direction C5' C4'
C3' C2'
BASE
γ
C3' C2'
BASE
γ
(gauche,gauche)
(gauche,trans)
(trans,gauche)
4' 1'
Nucleobase
C3'-endo
found in
A DNA helices
1'
3' 2'
4'
5'
3'
2'
4' 1'
Nucleobase
C2'-endo
found in
B DNA helices
3'
2'
Common sugar puckers
O 2 = O at position 2 of pyrimidine
O 4 '
pyrimidine (C, T, U) O 2
C2'
C3'
O 4 '
O 2 pyrimidine (C, T, U)
C2'
C3'