Synthetic constructs functionally mimicking ribonuclease A

The mechanism of hydrolysis of RNA substrates—diribonucleoside monophosphate CpA and decaribonucleotide UUCAUGUAAA—by chemical constructs functionally mimicking ribonuclease A was studied. It is shown that RNA cleavage by chemical RNases 2L2 and 2D3 proceeds similar to the RNase A-induced RNA hydrolysis through 2′,3′-cyclophosphate as an intermediate product. A comparison of hydrolyses of CpA in water and D₂O revealed an isotope effect (K _H/K _D=2.28), which implies acid-base catalysis at the limiting stage of the reaction. Two feasible mechanisms of RNA hydrolysis by chemical RNases (linear and adjacent) are discussed.