Enzymic Oligopeptide Synthesis Using a Minimal Protection Strategy: Sequential Assembly of a Growing Oligopeptide Chain

An approach to the enzymatic synthesis of oligopeptides is described which relies upon the selectivities of the enzymes employed rather than on the differential protection of the substrates for obtaining the desired sequences. Serine and cysteine proteases were shown to posess the selectivity required to differentiate among ester substrates of similar reactivity, thereby allowing the N to C assembly of an oligopeptide by the stepwise addition of amino acid esters without the requirement for intermediate deprotection steps. The applicability of this approach to the preparation of multifunctional peptides was demonstrated by the 10-step synthesis of “delicious octapeptide” amide with an overall yield of 39%.