An enzyme, which is probably identical with polynucleotide
phosphorylase, was prepared from Escherichia coli B. In the
presence of Mn2+ it catalyzes the addition of one (and to a
slight extent more) residue of deoxyribonucleotide residue from
the diphosphate to an oligodeoxyribonucleotide primer. The
shortest effective primers contained three phosphate residues.
Ribodinucleotides were effective as primers and accepted two
or three deoxyribonucleotide residues under these -ondit ions.
The application of the procedures to the convenient synthesis
of certain defined oligodeoxyribonucleotides up to nine residues long is discussed.