Uridine cyclic 3 ,5 -phosphate, preparation

Treatment of 2 -deoxyuridine derivatives of type 16 with a polymer-supported fluoride at room temperature gave the 2,3 -anhydrosystems 17 in good yield. The 8,5 -cyclonucleoside 18 was prepared by intramolecular displacement of an 8-bromosubstituent, and the conformationally fixed uridine cyclic phosphate 19, and the corresponding 2,5 -compound, have been prepared to study the effect of the conformation on their hydrolysis by ribonuclease. ... 

It must be emphasized that much of the information on the enzyme to date comes from partially purified preparations. Even though it seems uniquely specific for nucleoside 3, 5 -cyclic phosphates, the possibility cannot be excluded that in some tissues more than one diesterase may be present. In fact, Hardman and Sutherland (64) have shown that a second 3, 5 -cyclic phosphate diesterase exists in heart muscle which is primarily specific for uridine 3, 5 -cyclic phosphate. This enzyme was found to be more sensitive to inhibition by theophylline and to activation by imidazole. Further studies are needed to clarify its precise status other such enzymes may be discovered in the future. 

The sugar configuration about the T, 2, 3, and 4 positions can be changed by synthesis. A variety of pyrimidine nucleoside cyclic phosphates have been made. Ukita et al. (425) prepared -D-lyxo-uridine 2 3 -cyclic phosphate (Fig. 21a). The configuration about the 2 and 3 positions is inverted and the two OH groups are now cis to the base rather than trans as in the D-ribose series. No hydrolysis at all of this compound was observed in the presence of RNase. However, both the cyclic phosphate and the free 2 (3 )-nucleotides inhibit the enzyme. The... 

Ribonucleoside 2 3 -cyclic phosphate have been prepared by phosphorylation of the 5 -0-acyl derivatives of adenosine and uridine with P -diphenyl P -morpholino pyrophosphorochloridate (63), followed by treatment with dilute ammonium hydroxide. An interesting innovation... 

The first step in these reactions is probably the formation of the mixed phosphates (198), as such compounds were obtained by Hall and Kho-rana in a similar reaction conducted at 60°. It has been suggested that formation of the anhydronucleoside (199) occurs by attack of the 2-carbonyl group on C-2, with elimination of a pyro- or poly-phosphate group. An alternative mechanism may also be postulated, namely, that a cyclic pyrophosphate derivative (202, R = H or POsHa) is formed in the reaction with polyphosphoric acid, and that this then undergoes attack by the 2-carbonyl group on C-2. By a similar reaction-sequence, the 3, 5 -diphosphate of l-/3-D-arabinofuranosyluracil was prepared from uridine. ... 

D-Glucose 2-phosphate is formed as decomposition product of uridine diphosphate glucose with cyclic 1,2-glucose phosphate as intermediate . It has been prepared by phosphorylation of r,3,4,6-tetraacetyl-/ D-glucose with diphenyl phosphorochloridate . 

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