Trypsin-specific acyl-4-guanidinophenyl esters for alpha-chymotrypsin-catalysed reactions - Computational predictions, hydrolyses, and peptide bond formation

The function of acyl-4-guanidinophenyl esters as substrate mimetics for the serine protease alpha-chymotrypsin was investigated by protein-ligand dock ing, hydrolysis, and acyl transfer experiments. On the basis of protein-lig and docking studies, the binding and hydrolysis properties of these artific ial substrates were estimated. The predictions of the rational approach wer e confirmed by steady-state hydrolysis studies on 4-guanidinophenyl esters derived from coded amino acids (which alpha-chymotrypsin is not specific fo r), noncoded amino acids, and even simple carboxylic acid moieties. Enzymat ic peptide syntheses qualify these esters as suitable acyl donors for the c oupling of acyl components far from the natural enzyme specificity, thus co nsiderably expanding the synthetic utility of alpha-chymotrypsin.