[Analysis of poly(dA).poly(dT) structure by Raman spectroscopy and lattice dynamics].
Poly(dA).poly(dT) is a kind of DNA which one strand contains adenine(A) bases, and the other only thymine(T) bases. This DNA possesses flexible structure and the X-ray diffraction for poly(dA).poly(dT) fiber gives three different structures. So it is of interest to study poly(dA).poly(dT) structure in solution. In this paper, Raman spectrum of poly(dA).poly(dT) in 0.2 mol.L-1 NaCl solution was recorded over the spectral range 750-1000 cm-1. The Raman bands at 817 cm-1 and 843 cm-1 exist simultaneously. This implied that the secondary structure of poly(dA).poly(dT) is neither A-conformation nor B-conformation. Normal mode analysis of heteronomous secondary structure from poly(dA).poly(dT) fibers was carried out by the lattice dynamics. Normal modes were assigned by potential energy distribution (PED). The calculated frequencies are good agreement with the observed Raman spectrum. This indicated that poly(dA).poly(dT) in solution probably has the same structure as poly(dA).poly(dT) fiber, namely the poly(dA) chain has the C-3'-endo ring pucker while the poly(dT) chain has the C-2'-endo ring pucker.
Meng
Y
Y
Institute of Laser Life Science, South China Normal University, 510631 Guangzhou.
Liu
S
S
D004247:DNA / Q000737:chemistry*; D006801:Humans; D008968:Molecular Conformation; D009690:Nucleic Acid Conformation; D011067:Poly dA-dT / Q000737:chemistry*; D012996:Solutions; D013059:Spectrum Analysis, Raman; D013329:Structure-Activity Relationship; D014961:X-Ray Diffraction
D012996:Solutions; D011067:Poly dA-dT; D004247:DNA