The isolation and composition of ribonucleic acids from leaves

Abstract

Methods for the extraction of nucleic acids from leaves were devised and their efficiency studied. The most efficient methods depended on extraction with 1.7 [image] sodium chloride or 1.7 [image] diethyl-amine hydrochloride at 100[degree]. About 80% of the nucleic acid extracted with neutral 1.7 [image] sodium chloride was precipitated on standing at 0[degree]. This nucleic acid, like that obtained by extraction with 1.7 [image] diethyl-amine hydrochloride at 100[degree], was precipitated without loss by dilute Al3+ ions at pH 3. All preparations were composed mainly of poly-nucleotide, the greater proportion of which was RNA. The DNA content varied widely, from 2 to 27% of the total polynucleotide. The nucleotide composition of a large number of preparations, including some from sugar beet heavily infected with a necrotic strain of sugar-beet yellows virus was determined, and no biological significance has been attached to the small variations of composition that were found. The major nucleotide components of the RNA from the leaves of 4 plant species were more fully identified. The samples were extracted by the most exhaustive procedures for separating nucleic acid, and the P compounds remaining in the leaf residues were extracted and shown to be free from nucleotides. Electrophoresis and chromatography of the products of hydrolysis of these samples, followed by the measurement of spectral characteristics, showed the presence in quantity of only AMP, GMP, CMP and UMP (2[image]- and 3[image]-isomers), and there was no evidence of the presence of other nucleotides, or nucleosides, in more than trace quantities. Preliminary studies by indirect methods suggest that effectively the whole of the purine-bound and pyrimidine-bound sugar is ribose.