A Novel Chemoenzymatic Approach to Produce Cilengitide Using the Thioesterase Domain from Microcystis aeruginosa Microcystin Synthetase C

Modern organic chemistry faces many difficulties in the reliable production of cyclopeptides, such as poor yields and insufficient regio- and stereoselectivity. Thioesterase (TE) shows impressive stereospecificity, region- and chemoselectivity during the cyclization of peptide substrates. The biocatalytic properties of TE provide high value for industrial applications. Herein, a novel chemoenzymatic method to synthesize cilengitide is described based on the cyclic activity of the TE domain from microcystin synthetase C (McyC) of Microcystis aeruginosa. In addition, a single active site mutation in the McyC TE was engineered to generate a more effective macrocyclization catalyst. Compared to the chemical approach to synthesize cilengitide, this novel enzyme-catalysed methodology exhibits a higher synthetic efficiency with an approximately 3.4-fold higher yield (49.2%).