ABSTRACT
By 1984, the quest to understand the internal dynamics of protein molecules had created a pressing need for well-refined, high resolution data on protein structures. In a landmark contribution to the field of protein crystallography. Wlodawer, Walter, Huber, and Sjolin undertook an innovative joint application of X-ray and neutron diffraction methods to determine the structure of a new crystal form of bovine pancreatic trypsin inhibitor (BPTI). This work was the first to determine the atomic positions in a protein of this size to within the diameter of a hydrogen atom. It also established that joint X-ray-neutron refinement could produce structural detail consistent with the then emerging technique of two-dimensional NMR protein crystallography and provided the baseline data for the further development of multi-dimensional NMR. X-ray and neutron beams falling on a crystal are diffracted by its atomic constituents, and the periodic structure of the crystal causes the diffracted rays to be sharply defined.
