An analysis of dendritic cooperativity in protein hydrolysis
O'Dell, Jacob Webb
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Catalysts are compounds that increase the rate of a chemical reaction by lowering the activation energy while not being permanently altered. Adding a catalyst to a reaction, while increasing the rate, complicates purification because the catalyst must be separated from the product(s) of the reaction. If the catalyst is a drastically different size than the product then seperation can be achieved as easily as filtering over a membrane. Dendrimers are becoming popular scaffolding for tethering catalysts. Attaching a catalyst to a dendrimer makes a bigger catalytic unit that is easily separated from reaction product(s) of similar size to the untethered catalyst. However, attaching a catalyst to a dendritic framework usually results in a decrease in the catalystαs activity. Previous work reported that attaching three salicylic acid residues in close proximity to each other on a linear PPI polymer catalyzed the hydrolysis of the protein immunoglobulin Gαs peptide backbone. Attaching three salicylic acid residues at random locations on the polymer showed significantly less catalytic activity. Salicylic acid functionalized generations 1-5 PPI dendrimers were synthesized and characterized. Rate enhancement of IgG hydrolysis by the functionalized dendrimers was studied with SDS-PAGE. Generation 5 salicylic acid functionalized PPI dendrimers catalyzed the hydrolysis of IgG while lower generations and 5-nitrosalicylic acid did not. Generation 5 salicylic acid functionalized dendrimers catalyzing IgG hydrolysis is another in a small number of examples of catalytic systems enhanced by dendritic scaffolding.