The superiority of the carbamoylmethyl ester as an acyl donor for the α-chymotrypsin- catalysed kinetically controlled peptide-bond formation is demonstrated in the couplings of an inherently poor amino acid substrate, Ala, with various amino acid residues as amino components and in the couplings of non-protein amino acids such as halogenophenylalanines as carboxylic components. Furthermore, this approach is ...