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Biocatalysts: The Different Classes and Applications for Synthesis of APIs
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Transaminases (or aminotransferases) are enzymes transferring an amino group (EC 2.6.1.-). In the recent past, the use of PLP-dependent ω-transaminases (ω-TA; meanwhile (R)- and (S)-selective ω-TAs are known) for the synthesis of optically pure amines gained increasing interest in connection with the synthesis of active pharmaceutical ingredients (for reviews see, e.g., Fuchs et al., 2015; Simon et al., 2014). ω-TAs catalyze the reversible amination/deamination of suited substrates to yield optically pure amines either by kinetic resolution (one amine enantiomer is converted into a ketone whereas the desired amine enantiomer is left behind) or by asymmetric synthesis starting from a prochiral ketone. In these cases, the amine donor is l-alanine that is converted to pyruvate. In order to shift the equilibrium to the product side, the keto acid is converted to lactate in presence of lactate dehydrogenase; pyruvate decarboxylase has also been used for this purpose. Alternatively pyruvate may be recycled to alanine in presence of a alanine dehydrogenase. Very promising is the recently described use of o-xylylenediamine as a low-cost non-chiral amine donor (Green et al., 2014); in addition, spontaneous polymerization of the aromaticisoindoleformed during the course of the reaction yields intensively colored derivatives which may serve as a high-throughput screening platform to identify ω-TA activities. These enzymes work not only in an aqueous buffer solution but also in organic solvents.
Greener Synthesis of Natural Products
Published in Ahindra Nag, Greener Synthesis of Organic Compounds, Drugs and Natural Products, 2022
Renata Kołodziejska, Renata Studzińska, Hanna Pawluk, Alina Woźniak
Transaminases (TAs) classified as transferases, participate in the metabolism of amino acids, transform the carbonyl function into an amino moiety. The transaminase-catalyzed reaction requires pyridoxal phosphate (PLP) as a cofactor. Of the two types of PLP-dependent TAs classified according to the type of substrate they convert, the use of α-TAs, exclusively converting α-amino and α-keto acids, is more limited, while ω-TAs can accept substrates with a distal carboxylate group. Depending on the type of transaminase, both keto acids and ketones are tolerated as substrates, thus leading to enantiomerically enriched amino acids and amines, respectively (Figure 14.13).42–44
Treatment and high value utilization of glutamic acid wastewater
Published in Preparative Biochemistry & Biotechnology, 2022
Fupeng Yu, Chen Zhao, Le Su, Song Zhang, Xin Sun, Kunlun Li, Qiulin Yue, Lin Zhao
The fermentation of polyglutamate is related to the TCA cycle, and glutamate is an essential substrate for synthesis. The glutamate precursor in this study comes from glutamate waste liquid, and its involved pathway is related to D-amino acid transaminase. The synthases of polyglutamic acid are complex, mainly including enzymes related to the TCA cycle, such as citrate synthase, cis-aconitase and ketovalerate dehydrogenase.[36] and glutamate-dependent ATPase. As shown in Figure 11, the fermentation process was monitored in this study, and it can be found that with the increase of bacterial mass, the production of polyglutamic acid gradually increased, and the content of total sugar also gradually decreased. This was because the growth metabolism of Bacillus licheniformis consumed glucose.[37] Combined with the literature, it was speculated that glucose was involved in normal growth and glycolysis pathways. Under aerobic fermentation conditions, more carbon sources flowed into the TCA cycle, increasing the concentration of glucose 6-phosphate and affecting the synthesis of pyruvate, while the increase in pyruvate concentration also loops through the TCA. Promote the synthesis of α-ketoglutarate, and then synthesize a large amount of L-glutamic acid to generate γ-polyglutamic acid.
Enhancing the production of poly-γ-glutamate in Bacillus subtilis ZJS18 by the heat- and osmotic shock and its mechanism
Published in Preparative Biochemistry & Biotechnology, 2020
Yichao Song, Yishu Zhang, Min He, Hang Liu, Chunyu Hu, Liuzhen Yang, Ping Yu
To date, the biosynthetic pathway of endogenous glutamate, the precursor of the γ-PGA biosynthesis, was unclear. Ashiuchi et al.[11] proposed the existence of three glutamate metabolic pathways in microorganisms: (1) glutamate dehydrogenase catalyzed the generation of glutamate from α-ketoglutaric acid and inorganic ammonia in the absence of glutamine in the medium; (2) aminotransferase catalyzed the transamination reaction of amino acids with α-ketoglutaric acid to produce glutamate; (3) when glutamine existed in the medium, glutamate synthase catalyzed the reaction of α-glutaric acid with glutamine to form glutamate. Peng et al.[35] found that the biosynthetic pathways of glutamate in B. methylotrophicus included amino acid transaminase pathway, glutamate synthase pathway and glutamine synthase pathway.
Proteomics investigation of molecular mechanisms affected by EnBase culture system in anti-VEGF fab fragment producing E. coli BL21 (DE3)
Published in Preparative Biochemistry and Biotechnology, 2019
Bahareh Azarian, Amin Azimi, Mahboubeh Sepehri, Vahideh Samimi Fam, Faegheh Rezaie, Yeganeh Talebkhan, Vahid Khalaj, Fatemeh Davami
One arginine catabolism pathway in E. coli is arginine decarboxylase (ADC) which results in production of putrescine.[19] Putrescine is further degraded to succinate through two pathways: transaminase pathway and glutamylated pathway. The contribution of these two pathways is controlled by temperature. In culture temperature of our experiment, 37 °C, transaminase pathway is the dominant degradation pathway.[20] ABALDH, the second enzyme in transaminase pathway of putrescine degradation in 6 hr phase, is expressed only in EnBase cultured cells. Degradation of putrescine into succinate can replenish the tricarboxylic acid (TCA) cycle intermediates and enable the higher metabolic activity required for protein expression. Increase in TCA cycle activity in cells with plasmid encoded proteins has been reported in other studies.[13,21]