The interaction of HeLa cell heat denatured DNA with polyglucose.

The aqueous phase in phenol extracts of HeLa cells contain deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and polyglucose (CHO), (Segovia et al. , 1965). -RNA reacts with the CHO and they coprecipitate in 20% ethanol-saline solutions (Graves et al., 1967). -Native DNA precipitates when the ethanol concentration is increased to 50%. Although native DNA and CHO have equal buoyant densities in CsCl (Segovia et al., 1965) -and both precipitate in 50% ethanol, the present data from analytical centrifugation indicate that these findings were not due to intermolecular bonding. In contrast, the following experiments demonstrate that heat denatured DNA which is soluble in 50% ethanol precipitates from this solution in the presence of CHO when the ratio of CHO/DNA approaches 2. 5. The coprecipitation of CHO and DNA indicates that denatured DNA reacts with CHO, thus decreasing the solubility of the denatured DNA. MATERIALS AND METHODS HeLa cells were grown in monolayer cultures using Eagle’s (Eagle, 1955) medium supplemented with 10% heat-inactivated calf serum. The cells were extracted with phenol (Colter et al -.’ 1962). The RNA-CHO and DNA were successively precipitated in 20% and 50% ethanol solutions (Segovia et al -” 1965). The RNA was removed from the CHO by precipitation with trichloroacetic acid (Graves et al., 1967) and the acid-soluble GHO was -recovered by precipitating it with ethanol (66%). DNA and CHO were dissolved in phosphate buffered saline (PBS) 0. 005 M, pH 7. 2. The DNA was quantitatively determined with the Burton (Burton, 1956) method and CHO with a diphenylamine reagent (Snell and Snell, 1953; Ackermann et al -.’ 1964). In analytical ultracentrifugation experiments the CHO, DNA and