Thermodynamics of Na+ binding to coagulation serine proteases

The sodium binding to serine proteases triggers a conformational change in the proteins that enhances the catalytic activity of the enzymes. The inter action of the cation with-the protein is mediated by the hydrogen-bonding n etwork of water molecules that embed the Na+ site. We pointed out the cruci al role of the insertion loop 186a-d and the I16-D194 ion pair in the stabi lization of sodium binding pocket in thrombin. This paper contributes to be tter explain the molecular mechanism of sodium binding for different serine proteases leading to the identification of the structural changes necessar y to engineer a functional Na+ site and regulate catalytic activity in seri ne proteases. (C) 2001 Elsevier Science B.V. All rights reserved.