The structure of ribonucleic acids. 1. Cyclic nucleotides produced by ribonuclease and by alkaline hydrolysis

Abstract

If, however, a similar compound is obtained from a reaction mixture containing the C2OH260 compound its properties suggest C25H340, i.e. it derives from the C2oH260 compound. SUMMARY 1. Oppenauer oxidation of vitamin A using diethyl ketone as hydrogen acceptor results in a complex mixture from which a compound C2OH260 (isomeric with retinene2) can be isolated. It gives an oxime, m.p. 175177o, isolated by previous workers. 2. The C20H260 compound, is reducible in vitro and in vivo, but the product differs from vitamin A2. 3. The Oppenauer oxidation seems to proceed via retinenel, C20H280, which can either be further dehydrogenated to C20H,60 or can condense with diethyl ketone, to a ketone C25H360. Condensation of the C20H260 compound with diethyl ketone to yield C2,H..O is not excluded. 4. Vitamin A acetate is not dehydrogenated directly to vitamin A2. We wish to thank the Medical Research Council for financial support.

Nucleotide exchange reactions catalysed by ribonuclease and spleen phosphodiesterase. 1. Synthesis and interconversion of simple esters of ribomononucleotides

“…Solvent 1: i8opropanol-water (70:30, v/v), with NH, in the vapour phase (Markham & Smith, 1952). This solvent was generally used for the separation of products after incubation with enzyme.…”

“…Digestion of RNA with ribonuclease results in the splitting of all pyrimidine-pyrimidine internucleotidic links and of those pyrimidine-purine internucleotidic links which involve C(3w) of the pyrimidine nucleotide (Schmidt et al 1951;Markham & Smith, 1952;Merrifield & Woolley, 1952;Volkin & Cohn, 1953). The first stage in the degradation involves the formation of pyrimidine nucleogide-2':3' phosphates (cyclic nucleotides) and the simultaneous splitting of the internucleotidic phosphoester bond distal to C(31) ofthe latter.…”

“…The first stage in the degradation involves the formation of pyrimidine nucleogide-2':3' phosphates (cyclic nucleotides) and the simultaneous splitting of the internucleotidic phosphoester bond distal to C(31) ofthe latter. Thus it is possible to isolate from early ribonuclease-digests of RNA pyrimidine cyclic nucleotides and small polynucleotides comprised of purine nucleotide(s) terminating in a pyrimidine cyclic nucleotide (Markham & Smith, 1952). Further treatment with ribonuclease hydrolyses these pyrimidine cyclic nucleotides giving pyrimidine nucleoside-3' phosphates only (Brown, Dekker & Todd, 1952;Markham & Smith, 1952).…”

“…1955, 60 I Cyclic nucleotide&. The 2':3' phosphates of cytidine and ujd,ipe were isolated from ribonuclease-digests of RNA as ,sbiledby Markham & Smith (1952). The purine cyclic nft?…”

“…The purine cyclic nft? .4.otides were isolated by a slight modification of a revi m ublished procedure (Markham & Smith, 1952 of Whatman no. 3MM filter paper (25 x 50 cm.)…”