Phosphoric acid nucleoside 3 5 -cyclic

When AMP is heated under reflux in DMF, the 2, 3 -cyclic phosphate is formed, and cyclic phosphates can also be obtained from nucleosides and ortho-, pyro-, or poly-phosphoric acids under the same conditions. Promotion of phosphorylation by DMF is well known and the reaction with AMP is probably intermolecular as no 3, 5 -cyclic AMP can be detected. Minor products in the latter reaction are the 2, 3 -cyclic 5 -diphosphate and the 2 (30,5 -diphosphate. The synthesis of adenosine 2 (3 )-phosphate 5 -pyrophosphate has been achieved by the phosphoromorpholidate method used in a synthesis of Co A. ... 

In both DNA and RNA, the cyclic amine base is bonded to Cl of the sugar, and the phosphoric acid is bonded to the C5 sugar position. Thus, nucleosides and nucleotides have the general structures shown in Figure 24.15. (In discussions of RNA and DNA, numbers with a prime superscript refer to positions on the sugar component of a nucleotide numbers without a prime refer to positions on the cyclic amine base.)... 

Urea is another prebiotic condensing agent for the phosphorylation of nucleosides. Condensed phosphates have been obtained from ammonium phosphate and urea [126], while alcohols are easily phosphorylated at 150 °C by urea and phosphoric acid [127]. When an equimolar mixture of uridine 48 and Na2HP04 was heated at 100 °C in the presence of a ten-fold molar excess of urea and ammonium chloride, 97% of the phosphate was found to be incorporated into the nucleoside moiety mainly as uridine 5 -monophosphate 49 and uridine 2, 3 - cyclic phosphate 50 (Scheme 23). 

DNA is not easily hydrolyzed to nucleotides by acid or base. This can now be explained as due to the impossibility of forming cyclic triesters before hydrolysis, since there is no hydroxyl group on C2. Likewise C2 is not available for internucleoside links in DNA. The results of titrating DNA can be explained by the dissociation of 1 secondary phosphoryl group for every 10 to 20 nucleotides in addition to the amino and — NH—CO— dissociations of the purines and pyrimidines. Thus there is 1 triester and 1 monoester of phosphoric acid in 10 to 20 diesters. Branching is at a minimum. Enzymatic hydrolysis results in nucleoside-5 -phosphates. Supported by physical data, the concept of the DNA molecule is that of a long, slightly branched chain structure of C3 nucleotides linked to each other by a phosphoester bond at Cb. ... 

The enthalpies for the hydrolysis of a number of glycoside and nucleoside cyclic phosphates have been measured. Photolysis of the disodium salt of a-D-glucopyranose 6-phosphate in aqueous solution furnished a number of products, including D-gluconic acid 6-phosphate, D-arabinofuranose 5-phosphate, D-glyceric acid 3-phosphate, glycolic acid phosphate, phosphoric acid, and... 

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