Reverse hydrolysis by cardosin A: specificity considerations

Cardosin A, a plant aspartic proteinase, capable of synthesising peptides, was investigated through synthesis of five methyl esters amino acid substrates as amino donors and nine benzyloxycarbonyl amino acid and peptide carboxyl donors. It was found that cardosin A is able to catalyse the synthesis of several peptide bonds, being the preference order for the carboxyl components the following: CBz.Phe>CBz.Trp. Unpredictably, Tyr could not be accepted in P₁. Results were compared and discussed according to the known specificity of pepsin, the most studied aspartic proteinase.