Plenary Talk
Todd Yeates, Department of Chemistry and Biochemistry, University of California, Los Angeles
Finding and Designing Novel Knotted Protein Structures
In comparison to DNA, proteins are considerably shorter polymers. Furthermore, their geometry makes them less prone to exhibit topological complexity, particularly since the backbone of a protein molecule does not tend to wind around itself in the same way as DNA. Nonetheless, problems of knotting are relevant for protein folding. Randomly folded polymers as long as medium to large proteins would be expected to be knotted a significant fraction of the time. Yet, less than 1% of all known protein folds are knotted. This observation has important implications for fundamental ideas in protein science, such as whether it is reasonable to believe that the observed structures of natural proteins really represent their global free energy minima -- a dogma postulated by Anfinsen's Thermodynamic Hypothesis. Furthermore, the kinetic challenge proteins apparently face in folding into knotted configurations raises interesting questions about how those rare proteins that are indeed knotted