Hydrodynamic determination of polynucleotide chain discontinuities. Improved molecular weight correlations for denatured DNA.

Evidence is presented of the constancy in the conformation of denatured DNA in 2% formaldehyde in SSC (0.15 M NaCl/0.015 M trisodium citrate (pH 7.0)) over a wide range of molecular weights. It is also shown that denatured RNA behaves in the same way as DNA. The range of molecular weights studied runs from 0.02 to 16 X 10(6). In accordance with these results, biparametric expressions are proposed for molecular weight calculations from sedimentation or viscosity data of denatured DNA or RNA, when determined in 2% formaldehyde in SSC. Testing of the expressions with standard DNA and RNA preparations showed good correlation.