Liver Ribonucleic Acid

Abstract

IT has previously been shown¹ that mammalian tissues contain, in addition to nuclear desoxyribonucleic acid (thymonucleic acid), appreciable amounts of pentose nucleic acid, which appears to be mainly a cytoplasmic constituent². Liver tissue, for example, is known to contain both a desoxyribonucleic acid similar to the thymus nucleic acid³ and a pentose nucleic acid¹. The latter has now been isolated from the liver tissue of the sheep. The finely minced liver is dehydrated with ethanol and the nucleic acids extracted with 10 per cent sodium chloride. They are precipitated with ethanol, and the barium salts fractionated by the method used by Jorpes⁴ for the pentose nucleic acid of the pancreas. The pentose nucleic acid is finally purified by precipitation from glacial acetic acid. The material so obtained is free from protein and from desoxyribonucleic acid. It is similar to yeast ribonucleic acid in its pentose content and in its absorption spectrum. Its contents of purine and easily hydrolysable phosphorus are consistent with a tetranucleotide structure with equi-molecular amounts of purine and pyrimidine. It appears to differ, therefore, from the pentose nucleic acid of the pancreas, for which a pentanucleotide structure has been suggested⁴.