Facile Synthesis of S‐Substituted L‐Cysteines with Nano‐sized Immobilized O‐Acetylserine Sulfhydrylase

Abstract

AbstractMany S‐substituted l‐cysteines are useful pharmaceutical intermediates but require a simple synthesis method. Here we developed enzymatic synthesis of several S‐aryl‐l‐cysteines and S‐benzyl‐l‐cysteine directly from O‐acetylserine (OAS) with immobilized O‐acetylserine sulfhydrylase CysM. Novel iron‐oxide magnetic nanoparticles (MNPs) with cobalt‐nitrilotriacetic acid function were prepared with a diameter of 80 nm in 75 % yield. Direct immobilization of His‐tagged CysM in the cell‐free extract on the MNPs via affinity attachment afforded stable nanobiocatalyst with 97 % enzyme loading efficiency and 93 % free enzyme activity. The immobilized enzyme catalyzed the biotransformation of benzylthiol and OAS to give S‐benzyl‐l‐cysteine in 88 % yield. The nanobiocatalyst also demonstrated high recyclability, retaining 95 % productivity in the fifth cycle. The immobilized CysM accepts various arylthiols to react with OAS, giving rise to a new synthesis route of several S‐substituted l‐cysteines in 60–96 % yield.