IMPROVEMENT OF DNA QUANTITATION FOLLOWING PROTEOLYTIC EXTRACTION

A reliable and sensitive method for quantitation of deoxyribonucleic acid (DNA) is described herein. It is based on a proteinase K digestion step followed by a fluorometric assay with 3,5-diaminobenzoic acid (Kissane and Robins, 1958). The method proved to be applicable to fresh liver and to hepatocytes either in suspension or in culture when attached to a collagen substratum. A linear relationship between biological sample size and fluorometric response was observed only if the assay was preceded by proteolytic extraction. Moreover, the method resulted in DNA values per fresh liver weight that were about 100% higher than values reported earlier. The data show that proteolysis results in a more exhaustive extraction of DNA from tissues and a better separation of extracted DNA from other tissue constituents interfering with the assay. © 1978.