Abstract by Kimberlee Larsen
Chemistry and Biochemistry
Crystallography of Proteins to Obtain Structural Data
The interaction between a hydrophobic amino acid and a salt bridge has been shown to greatly stabilize helical proteins. This three-way interaction contributes up to 1 kcal/mol of stability to the folded protein. We collected structural data to observe the orientations of the hydrophobic amino acid relative to the positive and negative charges of the three-way interaction. In obtaining the crystal structure, we found that the three-way interaction was actually occurring in the crystal-crystal packing structure between trimers. This makes it difficult to know whether the three-way interaction is contributing to thermodynamics of the liquid phase peptide We therefore changed the position of the residues so that they were inside the trimer coil and protected from crystal-crystal packing interactions. The thermodynamics of the structure was comparable to the original three-way interaction. The variant is in the process of being crystalized.