Search

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. [ABSTRACT FROM AUTHOR]

Carboxylic acid reductases (CARs) are well-known for their eminent selective one-step synthesis of carboxylic acids to aldehydes. To date, however, few CARs have been identified and characterized, especially from fungal sources. In this study, the CAR from the white rot fungus Pycnoporus cinnabarinus (Pc CAR2) was expressed in Escherichia coli. Pc CAR2′s biochemical properties were explored in vitro after purification, revealing a melting temperature of 53 °C, while the reaction temperature optimum was at 35 °C. In the tested buffers, the enzyme showed a pH optimum of 6.0 and notably, a similar activity up to pH 7.5. Pc CAR2 was immobilized to explore its potential as a recyclable biocatalyst. Pc CAR2 showed no critical loss of activity after six cycles, with an average conversion to benzaldehyde of more than 85% per cycle. Immobilization yield and efficiency were 82% and 76%, respectively, on Ni-sepharose. Overall, our findings contribute to the characterization of a thermotolerant fungal CAR, and established a more sustainable use of the valuable biocatalyst. [Display omitted] • The carboxylic acid reductase (CAR) from Pycnoporus cinnabarinus Pc CAR2 is a pH and thermotolerant enzyme. • Targeted immobilization of Pc CAR2 maintains essential conformational flexibility of the enzyme and enables recycling. • All known CARs from subtype IV are from Basidiomycetes. [ABSTRACT FROM AUTHOR]