3.4A Minor groove Major 36A groove 20A (a）
The DNA Double Helix Is a Stable Structure Forces That Stabilize Nucleic Acid Double Helix Hydrogen bonding in base-pairing -Hydrophobic interactions in base stacking -Electrostatical Interaction with cations in solution such as Mg2+. 51 3 Same strand stacking cross-strand stacking 3 5
The DNA Double Helix Is a Stable Structure Forces That Stabilize Nucleic Acid Double Helix – Hydrogen bonding in base-pairing – Hydrophobic interactions in base stacking – Electrostatical Interaction with cations in solution such as Mg2+ . 5’ 5’ 3’ 3’ Same strand stacking cross-strand stacking
Types of DNA Double Helix Type A:major conformation of RNA,minor conformation of DNA; Type B:major conformation of DNA; Type Z:minor conformation of DNA 51 3' 51 3' 51 3 A Z 3 Narrow 15 3' B Wide 5 3Left-handed5 tight Less tight Least tight
Types of DNA Double Helix • Type A: major conformation of RNA, minor conformation of DNA; • Type B: major conformation of DNA; • Type Z: minor conformation of DNA 5’ 5’ 3’ 3’ 5’ 5’ 3’ 3’ 5’ 5’ 3’ 3’ A B Z Narrow tight Wide Less tight Left-handed Least tight