Novel approach toward industrial aromatic nitriles via biocatalysis: From rational enzyme design to sustainable, energy-saving technology platform

An efficient and broadly applicable synthetic method for the industrial product class of aromatic nitriles is presented, which—in contrast to technical methods such as ammoxidation and substitutions with cyanide—proceeds at energy-saving low temperature and avoids the use of highly toxic cyanide. As catalysts, a set of regioselective enzymes based on the aldoxime dehydratase from Rhodococcus sp. N-771 were identified and, in part, designed by a combined experimental and modeling approach. Due to a tailor-made enlarged active site, the variants M29G and F306A converted meta- and para-substituted substrates with even bulky substituents such as phenyl. In addition, the process runs at high substrate loading (of up to 500 mM as demonstrated for a model process) and shows a promising substrate scope.