Altered mobility of polydeoxyribonucleotides in high resolution polyacrylamide gels due to removal of terminal phosphates.

We have compared the electrophoretic mobility of a series of polynucleotides differing solely by the presence or absence of a terminal phosphate. As expected, the effect of removal of a single terminal phosphoryl residue on electrophoretic mobility is dependent on the size of the polynucleotide and therefore is not constant. Removal of a phosphoryl residue from polynucleotides shorter than 30 nucleotides reduces the mobility the equivalent of one nucleotide. Between 30 and 50 nucleotides the reduction in mobility is approximately one-half a nucleotide, while above 50 nucleotides in size the effect of phosphate removal approaches zero.