191d
From Proteopedia
CRYSTAL STRUCTURE OF INTERCALATED FOUR-STRANDED D(C3T)
Overview
The crystal structure of d(C3T), solved at 1.4 A resolution, reveals that the molecule forms a four-stranded intercalated complex. It consists of two parallel-stranded duplexes, each of which is held together by cytosine-protonated cytosine base pairs. The two duplexes are intercalated with each other and have opposite strand orientation. The molecule has a flat, lath-like appearance, and the covalently bonded cytosines have a slow right-handed twist of 17.1 degrees. However, there is considerable asymmetry. On one of the flat sides, the phosphate groups are rotated away from the center of the molecule. They are held in this orientation by bridging water molecules that bind the NH of cytosine and a phosphate group of an opposite chain. There is also considerable microheterogeneity in the structure. The cytosine hemiprotonation occurs even at pH 7 where stable crystals form.
About this Structure
Full crystallographic information is available from OCA.
Reference
Crystal structure of intercalated four-stranded d(C3T) at 1.4 A resolution., Kang CH, Berger I, Lockshin C, Ratliff R, Moyzis R, Rich A, Proc Natl Acad Sci U S A. 1994 Nov 22;91(24):11636-40. PMID:7972115 Page seeded by OCA on Fri May 2 09:35:02 2008
