Application of several types of substrates to ficin-catalyzed peptide synthesis. 
The capability of ficin, a cystine protease, to form peptide bonds was investigated using several types of N-Boc-amino acid phenyl and naphthyl esters as acyl donor components.  Enzyme-catalyzed peptide synthesis was carried out under optimized reaction conditions of pH, acyl acceptor concentration and selection of the best yield organic solvent.  It used a condensation of N-Boc-Ala-OpGu and Ala-pNA as a model reaction.  The products were obtained in 72-96% yield using 10 different substrates, within a few minutes of reaction time.