Effect of ethanol on rat-liver ribonucleoprotein previously exposed to cold trichloroacetic acid

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Abstract
Nucleoprotein was obtained from a homogenate or cytoplasmic fraction of rat liver by precipitating with dilute trichloroacetic acid. When extracted either with cold absolute ethanol or 95% (v/v) ethanol partial solubilization of ribonucleic acid protein occurred in the presence of acid with simultaneous appearance of what seemed to be a lipoprotein-polynucleotide complex in the ethanol phase. In contrast, deoxyribonucleic acid protein under similar conditions is not apparently affected. Evidence is presented to suggest that the ribonucleic acid protein susceptible to the solubilizing action of ethanol in the presence of acid is of cytoplasmic origin. Chromatographic analysis of the hydrolyzate of the first ethanol extract of ribonucleoprotein precipitated with trichloroacetic acid indicates the presence of adenine, guanine, uridylic acid and cytidylic acid. When the liver nucleoprotein, obtained by precipitation and washing with dilute trichloroacetic acid, is extracted with cold absolute ethanol, the yield of ribonucleic acid obtained by subsequent extraction with 10% (w/v) NaCl solution is significantly reduced. The loss in the yield of ribonucleic acid can be avoided by eliminating the extraction of ribonucleoprotein with absolute ethanol after precipitation with trichloroacetic acid. These observations have obvious implications in nucleic acid-tracer studies.