Deoxyribonucleic acid synthesis using binding protein extracted from chick embryo fibroblasts

Claim 1

In the improved method of isolating nucleic acid binding protein from Rous sarcoma virus transformed or nontransformed chick embryonic fibroblast cells, said method comprising: sonicating said cells; separating the supernatant from the sonicated cells; passing the supernatant through an affinity column comprising DNA to absorb the binding protein; eluting the binding protein with a salt solution; the improvement which consists essentially of further purifying the binding protein by ion exchange chromatography comprising first passing the eluate through a diethylaminoethyl cellulose column to absorb nucleases, undesired enzymes, and other binding protein unrelated to the desired protein and obtain a leak-through, and then subsequently passing the leak-through material through a carboxymethyl cellulose column to absorb the nucleic acid binding protein and other unrelated binding proteins and then eluting the desired binding protein specifically with a salt solution.