Engineering of L-amino acid deaminases for the production of α-keto acids from L-amino acids

Abstract

α-keto acids are organic compounds that contain an acid group and a ketone group. L-amino acid deaminases are enzymes that catalyze the oxidative deamination of amino acids for the formation of their corresponding α-keto acids and ammonia. α-keto acids are synthesized industrially via chemical processes that are costly and use harsh chemicals. The use of the directed evolution technique, followed by the screening and selection of desirable variants, to evolve enzymes has proven to be an effective way to engineer enzymes with improved performance. This review presents recent studies in which the directed evolution technique was used to evolve enzymes, with an emphasis on L-amino acid deaminases for the whole-cell biocatalysts production of α-keto acids from their corresponding L-amino acids. We discuss and highlight recent cases where the engineered L-amino acid deaminases resulted in an improved production yield of phenylpyruvic acid, α-ketoisocaproate, α-ketoisovaleric acid, α-ketoglutaric acid, α-keto-γ-methylthiobutyric acid, and pyruvate. ARTICLE HISTORY

Bioproducts from high-protein algal biomass: an economic and environmental sustainability review and risk analysis

“…260 Biological or enzymatic deamination has also recently begun to gain traction for lab-scale and potential commercial production of a-keto acids. 261,262 Several types of enzymes have activity for this reaction, including amino acid oxidases, dehydrogenases, aminotransferases, and deaminases. [263][264][265][266] Like many of the deamination products described above, a-keto acids are versatile molecules in foods, feeds, pharmaceuticals, and chemical synthesis.…”

Overview on Multienzymatic Cascades for the Production of Non-canonical α-Amino Acids

“…The above-described systems can be expanded with the inclusion of biocatalysts allowing the production of the α-keto acid substrates from other low-cost materials, such as AAOs (section “Amino Acid Oxidase-Based MECs”), threonine deaminase (ThrD 3 , threonine ammonia lyase) or “real” amino acid deaminases. L -amino acid deaminases ( L -AADs, EC 1.4.99.B3, Molla et al, 2017 ; Melis et al, 2018 ; Nshimiyimana et al, 2019 ) have been described as membrane-bound cytochrome-like flavoenzymes that catalyze the oxidative deamination of different AAs for the formation of their corresponding α-keto acids and ammonia; they have gained interest in the last lustrum since they can replace LAAOs in biotechnological applications ( Molla et al, 2017 ). Both AAOs and AAD can thus be engaged to enantiocomplementary AADHs, for the theoretical production of L -α-AAs (DAAO/catalase/ L -AADH/cofactor recycling) or D -α-AAs [(LAAO/catalase) (or LAAD)/ D -AADH/cofactor recycling].…”

Exploration of Transaminase Diversity for the Oxidative Conversion of Natural Amino Acids into 2-Ketoacids and High-Value Chemicals

“…LAAD is considered a promising alternative to LAAO for biotechnological applications. 27 Nevertheless, it is a membrane-bound protein and requires a physiological membrane as the electron acceptor. 27 In addition, only a few LAADs are found in the Proteus species, 23 and such a limited gene pool severely hinders the discovery of new enzymes with an alternative substrate specificity or enhanced robustness.…”

“…27 Nevertheless, it is a membrane-bound protein and requires a physiological membrane as the electron acceptor. 27 In addition, only a few LAADs are found in the Proteus species, 23 and such a limited gene pool severely hinders the discovery of new enzymes with an alternative substrate specificity or enhanced robustness. Finally, ATs are ubiquitous enzymes found in all organisms and are broadly used as promising biocatalysts in the organic synthesis of chiral amino compounds, 24 but the application of AT for the preparation of 2-ketoacids has rarely been studied.…”

“…LAAD catalyzes a similar reaction as LAAO, but the electrons of the reduced cofactor are transferred to a cytochrome. LAAD is considered a promising alternative to LAAO for biotechnological applications . Nevertheless, it is a membrane-bound protein and requires a physiological membrane as the electron acceptor .…”