Preliminary results of neutron structural analysis of glucose isomerase under natural conditions during the enzyme reaction

Glucose isomerase binds two divalent metals and catalyzes the isomerization of glucose to fructose. In this study, a single crystal of the ternary complex of glucose isomerase from Streptomyces rubiginosus with glucose and magnesium was prepared, and the crystal structure was analyzed under more natural reaction conditions than in previous crystallographic studies. The two histidine residues that interact with the substrate and metal in the active site were singly and doubly protonated, respectively. We also observed the glucose substrate in two molecular states, cyclic and linear, as a result of analysis of the structure under natural reaction conditions.