Helical Forms

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Helical Parameters

 

A-
conformation

B-
conformation

Z-
conformation

B/Z
junction
 

 images

  images

  images

  images
 

 coordinates

 coordinates

 coordinates

 coordinates

Description

underwound/compact

long/narrow

Lh

Helical Sense

RH

RH

LH

Helical Diameter

26 Å

20 Å

18 Å

Twist/Base Pair

31°

36°

-30°

Rise/Base Pair

2.6 Å

3.3 Å

3.7 Å

Base Pairs/Turn

11

10

-12

Rise/Turn (pitch)

28 Å

34 Å

45 Å

Roll (r)

8.0°

0.6°

Propeller

-7°

-13°

Inclination

19°

-1 °

0 Å

x-disp

-5.2 Å

0.0 Å

0 Å

Groove Shape
     

Major Groove

Narrow, Deep

Wide, Deep

Convex Surface

Minor Groove

Wide Shallow

Narrow, Deep

Narrow, Deep

Sugar Pucker

C3'-Endo

C2'-Endo

C3'-Endo (Purines), C2'-Endo (Pyrimidines)

Glycosidic bond

(c)

Anti

Anti

Syn (Purines), Anti (Pyrimidines)