Cytidylic acid cyclic

Holy and Sorm (49, 50) observed that RNase T2, like RNase Ti, attacks 9-(/3-D-ribofuranosyl) and 9-(a-L-lyxofuranosyl) derivatives but not 9-(j8-L-ribofuranosyl) and 9-(a-D-lyxofuranosyl) derivatives. Also, like RNase RNase T2 is quite inactive on the phosphodiester bonds of the nucleotide with 2 -0-methyl ribose, such as 2 -0-methyl guanylic acid (96) or 2 -0-methyl cytidylic acid (86). Thus, the action of RNase T2 is in good accord with that of RNase Ti and RNase A on sugar specificity, which may be a common property throughout all RNases, producing 3 -phosphate via 2, 3 -cyclic phosphate. 

The possibility that, during the alkaline hydrolysis of ribonucleic acid, tri-esters (18) - could be intermediates was ruled out on mechanistic groxmds."f > Furthermore, it was shown that the tri-ester, uridine 2 3 -(methyl phosphate) (18, R = CH3), synthesized by methylation of uridine 2 3 -cychc phosphate with diazomethane, is resistant to ribo-nuclease. f However, it has been observed that, when the benzyl ester of cytidylic acid 6 is partially hydrolyzed in acid, a significant proportion of the o isomer of this phosphoric diester is formed." ) In addition, the dinucleoside phosphates, such as adenylyl-(3 —>5 )-cytidine (14a), are also isomerized to the corresponding (2 - 5 )-dinucleoside phosphates by treatment with acid. " These studies suggest that cyclic triesters (or derivatives thereof) may be intermediates in isomerization of these phospho-diesters in acidic mediiun. 

Cy tidy lie Acid. Cyridine-3 -monophosphate cytidylic acid b 3 -cytidinephosphoric acid cytidine-3 -phosphate 3 -cytosylic acid 3 -CMP, CjH NjOjP mol wt 323.19. C 33.44% H 4-37%, N 13.00%, O 39-61%. P 9 58% Ribonuclease inhibitor. Prepn from yeast ribonucleic acid see refs under 2 -Cytidylic Acid. Prepn by pancreatic-ribonuclease-catalyzed ring opening of dicyclohexy] -guanidinium cytidine 2 ,3 -cyclic phosphate Lohrmann,... 

Like all ribonucleases, pancreatic ribonuclease attacks phosphodiester linkages between the 3 and 5 positions of the RNA nucleotide moieties to yield 2, 3 -cyclic phosphate derivatives. The cyclic phosphates are then further hydrolyzed to yield the 3 -phosphate derivatives. The specificity of pancreatic ribonuclease is such that it restricts its activity to the phosphodiester bonds that involve 3, 5 -linkages between a pyrimidine and any other base. Therefore, the product of the ribonucleic acid digestion with ribonuclease contains 3 -pyrimidine mononucleotides and oligonucleotides with a 3 -cytidylic or uridylic mononucleotide. Taka-diastase (Tl) is a ribonuclease that attacks the polynucleotides to yield 3 guanosine mononucleotides and oligonucleotides with a terminal 3 -guanylic acid. 

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