Small X-Ray Diffraction of Immunoglobulin-Membrane Complexes.

In the first part of this research, specially designed hapten-phospholipid molecules were synthesized to enable the binding of immunoglobulins to artificial phospholipid membranes. In subsequent work, using these immunoglobulin-membrane complexes, electron microscopy was used to reveal the detailed crystalline structure of a two dimensional (2D) immunoglobulin crystal attached to an electron microscope grid. These studies enabled the discovery of a new conformational arrangement of crystals formed from intact immunoglobulin molecules. In a third part of the study, monolayers of protein-membrane complex (in this case the purple membrane from halobacterium halobium) were deposited on a single crystal silicon substrate. Using the technique of grazing incidence X-ray diffraction, diffraction patterns from a single monolayer of protein-lipid complex were obtained for the first time.