[Affinity modification of proteins, binding nucleic acids in mammalian cells, by alkylating derivatives of oligonucleotides].

Using the 32P-labelled alkylating oligonucleotide derivative (pT)16, the oligonucleotide interaction with mammalian cells has been studied. The majority of fibroblastoid cell lines tested in this study (COS-1, vero, L-671, Ag 17-1, CHO, B7) as well as mouse hepatocytes were found to contain proteins specifically interacting with oligonucleotides. Cells of Ag 17-1 and COS-1, apart from the 79 kDa protein specific for all fibroblast lines, contained also a protein with a molecular mass of 83 kDa. In BALB/c mouse hepatocytes the 83 kDa protein is the major oligonucleotide binding protein. Analysis of concentration dependencies of specific modification of receptor proteins in liver cells has made it possible to determine the values of constants for the oligonucleotide derivatives binding to the protein. The binding constant for the alkylating oligonucleotide derivative pT16 and the corresponding phosphothioate oligonucleotide has been found to be equal to 5 x 10(6) M-1.