A glycoprotein which binds to nucleic acids1 has now been purified from Ustilao maydis until free from detectable deoxyribonuclease activity. It binds to a variety of substrates and in doing so, makes them soluble in dilute trichloroacetic acid. Physical studies suggest that it forms a variety of aggregates under low ionic strength, but at high ionic strength the monomer consists of a single polypeptide chain. Preliminary experiments have detected this novel binding activity in bacterial, fungal and marmnalian cells. © 1979 Information Retrieval Limited.