PLP-dependent enzymes as important biocatalysts for the pharmaceutical, chemical and food industries: a structural and mechanistic perspective
Juliana F. Rocha, André F. Pina, Sérgio F. Sousa and Nuno M. F. A. Sousa Cerqueira
DOI: 10.1039/C9CY01210A | Catal. Sci. Technol.
Enzymes catalyze a plethora of chemical reactions in nature. These biocatalysts offer a variety of benefits that no other synthetic catalyst can offer: high turnover, regio- and stereoselectivity, and ability to work under mild conditions and to react in environmentally friendly manufacturing processes. However, enzymes are not normally optimally suited for industrial applications. It is important to improve their properties to enable their more efficient application in an industrial setting, while also expanding the range of potential chemical reactions that they can catalyze. In this review, we focus our analysis on structural features and mechanisms of different enzymes that contain a pyridoxal-5′-phosphate (PLP) cofactor and that have noteworthy potential as biocatalysts in a variety of industries and applications. The selected PLP enzymes are ω-transaminases, lysine decarboxylase, threonine aldolase, L-tyrosine phenol-lyase, α-amino-ε-caprolactam racemases, and cystathionine β-lyase. For each of these enzymes, the catalytic mechanism, industrial application, and the advantages and disadvantages of their application are reviewed in detail. In general, this review highlights the immense biocatalytic potential, rich chemistry and diverse set of applications that different enzymes sharing a common element (PLP) can offer.