The sucrose gradient and native DNA S20,W, an examination of measurement problems

Sedimentation coefficients of T7, T2H AND T4 DNA were determined with isokinetic sucrose gradients in both 0.1 M and 1 M NaCl. The s values were completely equivalent to those measured by analytical ultracentrifuge and no reduction of s20,w was observed due to the presence of sucrose (anomalous sedimentation). s20,w values are calculated on the basis of both partial specific volume (v) and apparent specific volume (0). Using the latter value s20,w molecular weight relations are derived for 0.1 M and 1 M NaCl solvents. The glucosylation of T2H and T4 DNA appears to influence s20,w in a manner disproportionate to the molecular weight added by glucose.