Protease-catalysed coupling of N-protected amino acids and peptides with 4-aminoantipyrine

The enzymatic synthesis of N-protected L-aminoacyl- and L-peptidyl-antipyrine amides was accomplished by proteases from different classes. Serine and cysteine proteases proved to be suitable tools for the production of amino acids and peptides conjugated to 4-aminoantipyrine, whereas metalloproteases do not seem to be very qualified for accepting this nucleophile. The product yields were optimised by applying ample opportunities of medium engineering, e.g. aqueous-organic, biphasic, suspension and solid-to-solid reaction systems. Thus, yields up to 100% could be obtained. The products were purified and characterised by polarimetry and NMR spectroscopy. These results broaden the common knowledge of the catalytic potential of proteases, in particular with regard to the suitability of a special heterocyclic 1,2-amino ketone as a nucleophile for the biocatalytic amidation of amino acids and peptides.