Biocatalytic carboxylate reduction – recent advances and new enzymes

Carboxylate reductases (CARs) are valuable catalysts for the selective one-step reduction of carboxylic acids to their corresponding aldehydes. In recent years, numerous new CARs have been made available, studied and applied in the context of biocatalytic syntheses. The preparation of aldehydes as end products for the flavor and fragrance sector and the integration of CARs in cascade reactions with aldehydes as the key intermediates represent the two major fields of applications. This review gives a comprehensive overview of the current toolbox of recombinant CARs and their numerous carboxylate substrates. Non-natural functions of CARs are highlighted and recent insight into the structure-function relationship of CARs are summarized.