Selectivity and specificity in substrate binding to proteases: novel hydrolytic reactions catalysed by α-chymotrypsin suspended in organic solvents with low water content and mediated by ammonium hydrogen carbonate

α-Chymotrypsin suspended in organic solvents with low water content catalysed hydrolytic reactions in the presence of ammonium hydrogen carbonate. Molecular modelling studies were carried out and structure–reactivity relationships were established by studying the hydrolysis of amino acid derivatives and analogues. The enzyme was found to be stereoselective with respect to the hydrolysis of L-amino acid derivatives, but no stereoselectivity was observed when α-hydroxy esters were used as substrates. A general procedure for the resolution of aromatic amino acid esters is given. The results are interpreted in terms of molecular modelling based on X-ray crystallographic data and literature data.