‘Active’ conformation of the inositol monophosphatase substrates adenosine 2′-phosphate and inositol phosphate: role of the ribofuranosyl O-atom and inositol O-atoms in chelating a second magnesium ion

Abstract

A high energy conformation, in which the adenine moiety of adenosine 2′-phosphate occupies a C-1′-axial ribofuranosyl position, is stabilised through the chelation of a second (additional) Mg²⁺ ion by the 2′-and furanose ring O-atoms; with inositol 1-phosphate as the substrate, the 1- and 6-O-atoms chelate the second Mg²⁺ ion and for both substrates a different (buried) Mg²⁺ ion interacts directly with the phosphate moiety.