The goals of this project are to obtain a picture of a protein and its solvent environment at atomic resolution and to test how well the mobility of atoms in the structure is modeled by molecular dynamics and normal mode treatments of protein motion. The test system for these studies is the well-ordered, hydrophobic protein, crambin, which diffracts to at least 0.83 A. An underlying motivation is to understand the forces which stabilize protein folding by determination of the protein's equilibrium geometry and vibrational motion and by calculating the magnitude of the interaction forces in the crystal with an empirical potential energy function. Crambin presents a unique opportunity to view a protein with its surrounding solvent at truly atomic resolution, unprejudiced by a restraining protein model. There are numerous benefits from this information. The geometry of the peptide unit can be seen for the protein itself. The hydrogen bonding distances and angular distributions both within the protein and for the water can be examined. The arrangement of water molecules around polar and nonpolar groups at the protein surface may provide a model for building water around other protein surfaces and for understanding water at the active sites of enzymes.
