Nucleoside-5′-Phosphates from Ribonucleic Acid

Abstract

THOUGH the manner in which the four nucleotides of ribonucleic acid are combined in the intact molecule is not completely settled, the data obtained from analyses of the chemical degradation products are most compatible with phosphoryl-group attachments through the C₂ and C₃ positions of the ribose group¹. The exclusion of C₅ phosphoryl linkages rests principally upon the failure to isolate 5′ nucleotides or the acid-stable ribose-5-phosphate from acid hydrolysates of ribonucleic acid. However, Gulland and Jackson², hydrolysing yeast ribonucleic acid with a snake venom containing a phosphodiesterase and a specific 5′ nucleotidase, found 35 per cent of the total phosphate liberated as inorganic phosphate, suggesting that a large number of the phosphoryl groups were attached to the ribose C₅ position. Recently, Schmidt³, utilizing periodate titrations of ribonuclease-hydrolysed yeast ribonucleic acid, concluded that some nucleotide groups had been linked to positions other than ribose C₂ or C₃ in the original ribonucleic acid. The experiments described below indicate that intact 5′ nucleotides can be isolated from enzymatically hydrolysed calf liver ribonucleic acid.