Right-handed double-helix ultrashort DNA yields chiral nematic phases with both right- and left-handed director twist.

ABSTRACT: Concentrated solutions of duplex-forming DNA oligomers organize into various mesophases among which is the nematic (N(∗)), which exhibits a macroscopic chiral helical precession of molecular orientation because of the chirality of the DNA molecule. Using a quantitative analysis of the transmission spectra in polarized optical microscopy, we have determined the handedness and pitch of this chiral nematic helix for a large number of sequences ranging from 8 to 20 bases. The B-DNA molecule exhibits a right-handed molecular double-helix structure that, for long molecules, always yields N(∗) phases with left-handed pitch in the μm range. We report here that ultrashort oligomeric duplexes show an extremely diverse behavior, with both left- and right-handed N(∗) helices and pitches ranging from m

SUBMITTER: Zanchetta G 

PROVIDER: S-EPMC2955086 | biostudies-literature | 2010 Oct

REPOSITORIES: biostudies-literature