Abstract
Protonation is the key to elucidate a function of protein.Neutron crystallographic analysis is a powerful method that can observe the protonation states of amino acid residues in a protein molecule. However the neutron crystallographic technique was very difficult method, because of low flux neutron source mainly. Recently, a neutron imaging plate and an elastically bent perfect Si monochromator enabled neutron experiment. As the result, neutron structural biology has been progressed greatly in these ten years. In this report, we explain the various biological reactions affected by the protonation state on protein molecules by our studies on neutron crystallographic analysis. Furthermore, we also introduce our recent study on the protonation of cubic insulin molecule.
