Dendrimeric Pyridoxamine Enzyme Mimics

PAMAM dendrimers from generations 1−6 were synthesized with pyridoxamine in their core. They transaminated pyruvic and phenylpyruvic acids in water to alanine and phenylalanine, respectively, with Michaelis−Menten kinetics and high effectiveness compared with simple pyridoxamine. The largest dendrimerssimilar in size to some globular proteinswere comparable in effectiveness to a previous polyethylenimine (PEI)−pyridoxamine catalyst, and to a protein−pyridoxamine catalyst, but not as effective as a previous PEI−pyridoxamine carrying lauryl hydrophobic groups. The new catalysts showed both general acid/base catalysis by their amino groups and hydrophobic binding of the phenylpyruvate substrate.