THE ACTIVE SITE OF BOVINE PANCREATIC RIBONUCLEASE: AN EXAMPLE OFSOLVENT MODULATED SPECIFICITY

Abstract

A dynamic role for conserved water molecules in modulating the substrate specificity of ribonuclease is proposed based upon X-ray and neutron crystallographic studies. The structures of ribonuclease complexed with a transition state and substrate analogs are compared with the high resolution structure of the unliganded enzyme. Two conserved water molecules change their donor-acceptor roles in hydrogen bonds for accommodation of either uracil or cytosine in the B1 pocket.