CYTIDYLATE CYCLASE - PRODUCT ISOLATED BY THE METHOD OF CECH AND IGNARRO IS NOT CYTIDINE 3', 5'-MONOPHOSPHATE

When mouse liver homogenates were incubated with [α-32P]-CTP according to the method of Cech and Ignarro (4,5), a [32P] product (100-120 pmoles/mg protein/minute) was isolated by chromatography on alumina column, in the same fraction as [3H]-cyclic CMP.1 1 Abbreviations: Cyclic CMP, cytidine 3′,5′-monophosphate. However this product did not behave as cyclic CMP in various chromatographic systems. Moreover the amount of this [32P] product isolated was markedly reduced by removal of protein prior to chromatography on alumina. Chromatography of the enzymatic reaction product either before or after alumina purification on Dowex 1 - formate column indicated that 5′-CMP and CDP are the major products, with no formation of cyclic CMP. These results indicate that the [32P] labeled material isolated by Cech and Ignarro is mainly if not entirely 5′-CMP and CDP. © 1979.