Comparative inhibitory activity of 3'- and 5'-functionalized nucleosides on ribonuclease A.

Modified nucleosides, molecules, functionalized with various polar groups at different positions have been synthesized to rationalize the impact of structural modification on their inhibitory activity. Agarose gel and precipitation assays indicate their improved inhibitory activity on ribonuclease A (RNase A). Kinetic experiments clearly categorize them as competitive inhibitors of RNase A with improved inhibition constant (K(i)) values (37±9, 67±6, and 193±7μM for compounds 10, 3, and 7, respectively). The preferential hydrogen bonding network formation between His-12 and His-119 of RNase A with the polar carboxylic and amino groups of these compounds has been evidenced from the docking studies. The relationship between structural modifications and inhibitory activity of these compounds is further justified in terms of energetics using PEARLS.