THE CORRELATION BETWEEN 13C CHEMICAL SHIFTS OF DNA AND INTERSTRAND PURINE-PURINE CLASH

The correlation between 13C chemical shifts of DNA and structure parameters （the mainaxis helix twist angle Ω, base--plane roll angle ρ, main chain torsion angle δ and pro-peller twist angle ω） has been discovered and proved indirectly. The carbons relating tothe structure parameters have been found and interpreted theoretically. Relative variationsin chemical shifts of these carbons obviously reflect purine-purine clash （steric hindrance）and have been compared with sum functions Σ of Calladine--Dickerson rules. It would bepossible to provide the information about conformation of DNA from 13C NMR spectra andto observe the structure parameters of Ω,ρ,δ and ω of DNA in solution.