Inosine 3 : 5 -cyclic phosphate

The sugar specificity of RNase Tx appears to require a 2 -hydroxyl group for the substrate because DNA is not attacked by RNase Tx. This is consistent with the intermediary formation of 2, 3 -cyclic phosphate and also with the finding that 2 -0-methylated guanylyl bonds in tRNA is resistant to the enzyme (48)- Holy and Sorm (49) found that RNase Tx did not attack L-guanosine 2, 3 -cyclic phosphate and L-inosine 2, 3 -cyclic phosphate. They found further that RNase Tx split 9-(a-L-lyxo-furanosyl)-hypoxanthine 2, 3 -cyclic phosphate but not the D-lyxofura-nose derivative, and they concluded that the substrate molecule was fixed at least to three regions of RNase Tx (50). 

The nucleotide inosine 3, 5 -cyclic phosphate H20 [BEPRAP] crystallizes in the zwitterionic form. The free oxygen atoms of the phosphate accept two strong, salt-type hydrogen bonds from two N(l)-H groups. 0(6) and N(7) are not involved in hydrogen bonding (Fig. 17.63). 

Miller, J. P., Boswell, K. H., Muneyama, K., Simon, L. N., Robins, R. K., and Shuman, D. A., 1973, Synthesis and biochemical studies of various 8-substituted derivatives of guanosine 3, 5 -cyclic phosphate, inosine 3, 5 -cyclic phosphate and xanthosine 3, 5 -cyclic phosphate. Biochemistry 12 5310. 

Ap4A, diadenosine tetraphosphate BBG, Brilliant blue green BzATP, 2 - 3 -0-(4-benzoyl-benzoyl)-ATP cAMP, cyclic AMP CCPA, chlorocyclopentyl adenosine CPA, cyclopentyl adenosine CTP, cytosine triphosphate DPCPX, 8-cyclopentyl-1,3-dipnopylxanthine IP3, inosine triphosphate lpsl, diinosine penta phosphate a,p-meATP, a,p-methylene ATP p.y-meATP, p.y-meihylene ATP 2-MeSADP, 2-methylthio ADP 2-MeSAMP, 2-methylthio AMP 2-MeSATP, 2-methylthio ATP NECA, 5 -W-ethylcarboxamido adenosine PPADS, pyridoxal-phosphate-6-azophenyl-2, 4 -disulfonic acid PLC, phospholipase C RB2, reactive blue 2 TNP-ATP, 2, 3 -0-(2,4,6-trinitrophenyl) ATP. 

Adenosine 3, 5 -cyclic phosphate166 8-Bromoguanosine dihydrate167 D-Ribofuranosyl-6-thiopurine168 Inosine 5 -(sodium phosphate) octahydrate169 5-Bromo-5-deoxythymidine (form B)170... 

Cyelo-IMP cyclic inosine 3, 5 -monophosphate. See Inosine phosphates. 

The cyclic N. (cyclic 3, 5 -monophosphates) have important regulatory properties (see Adenosine phosphates, Guanosine phosphates, Inosine phosphates. Uridine phosphates). 

---