Remarkably Distinctive Recognition of α-Alanine and α-Phenylalanine during the Water-Catalyzed Hydrolysis of an Activated Amide

The rate of the water-catalyzed hydrolysis of three activated amides in aqueous solution is significantly retarded by small amounts of α-phenylalanine as compared with the rate acceleration induced by other common α-amino acids not containing a benzyl group in their side chain. These contrasting effects emphasize the large hydrophobicity of α-phenylalanine and are of relevance for a better quantitative understanding of protein folding and molecular recognition processes involving proteins.