Synthesis and use of new semispecific substrates for trypsin-catalyzed peptide bond formation

Two series of semispecific acyl donors, hydroxyalkyl eaters of Z-Ala-OH and N-modified carboxamidomethyl (Cam) esters of Z-Xaa-OH (Xaa = Ala, Leu, Phe ) were synthesized as substrates for trypsin-catalyzed peptide synthesis. I t follows from the specificity constants of these compounds, that the carbo xamidomethyl derivatives are well accepted by trypsin due to favourable S-2 ' - P-2' interactions. These new substrates can be successfully used for th e trypsin-mediated formation of dipeptide amides. The synthesis outcome dep ends on the amino acid in the P-1 position, the ability of the leaving grou p to provide efficient interactions with the enzyme subsite and the hydroph obicity of the nucleophilic amino acid amide. The modified Cam esters give better peptide yields in comparison to the unmodified ones.