[Cation preferences of the DNA-polymerases in plasma from patients with leukaemia or breast cancer (author's transl)].

The reverse transcriptase in plasma from leukaemic patients perfers the divalent cation Mn++ to Mg++ in the polymerase assay. The reverse is true for the enzyme from plasma of patients with breast cancer. This cation preference is analogous to the cation preference found in B- and C-type RNA-tumour viruses.