Structure of bound water and refinement of acid metmyoglobin

In the structure of myoglobin as determined from x-ray diffraction data the positions of the hydrogen atoms cannot be described, but they are important factors in determining the interactions of the heme with its environment. Neutron diffraction work, done in this laboratory, has demonstrated that hydrogen and deuterium positions can be located. In addition to the localization of H and D, neutron diffraction provides a unique method for studying the water structure because of the strong scattering ability of D2O. The scattering factor of deuterium is nearly twice as large as that of hydrogen, and it increases the visibility of water molecules in Fourier maps, so that in a neutron map a water molecule appears about three times as strong as in an equivalent electron-density maps. The reciprocal-space refinement of acid metmyoglobin and in particular the details of the water structure and hydrogen exchange are presented here