A Simple Method for measuring Ribonucleic Acid Content of Preparations of Deoxyribonucleic Acid

Abstract

IN recent years an increasing number of varied biological activities have been found associated with highly purified DNA. It is of some importance, in interpreting the effects of DNA on biological systems, to determine quantitatively the RNA content of such DNA preparations. Unfortunately, at the present time there is no generally accepted standard procedure to estimate small amounts of RNA in the presence of high concentrations of DNA. The orcinol method^1,2, as is well known, gives falsely high RNA values because DNA itself reacts with the reagent to a limited extent. We have tested a variety of reported modifications of this orcinol procedure and have found them unsatisfactory. They have produced results indicating the presence of 5–10 per cent “RNA” in DNA preparations containing no demonstrable uracil after acid hydrolysis and paper chromatography (<3 per cent RNA). Therefore, a simple, rapid method, used successfully in this laboratory to estimate RNA content, appears to be worth reporting.