The project proposed here focuses on ligand-induced changes in dynamics of pheromone-binding proteins. Mouse MUP-I, previously studied by the joint applicant, was chosen as a protein model. Dynamic parameters describing amide bond motions will be estimat ed from relaxation data for the free protein and for MUP-I complexed with a native pheromone and pheromone analogs. Following introduction of advanced techniques of isotope labeling (alternating 13C labeling with partial deuteration), the dynamic measure ments will be extended to side-chain C-H bonds. Effects of ligand binding on conformational entropy will be evaluated from values of the order parameter and compared with calorimetric data. Computational methods will be introduced to address other free e nergy changes upon ligand binding. Solution structures of free MUP-I and of its complex with the bound pheromone will be solved by NMR and compared with crystal structure obtained by a collaborating group. Application of the mentioned methodology to MUP-

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