ChemInform Abstract: Engineered‐Serine Hydroxymethyltransferase from Streptococcus thermophilus for the Synthesis of α,α‐Dialkyl‐α‐Amino Acids.

Abstract

a,a-Disubstituted a-amino acids are central to biotechnological and biomedical chemical processes for their own sake and as substructures of biologically active molecules for diverse biomedical applications. Structurally, these compounds contain a quaternary stereocenter, which is particularly challenging for stereoselective synthesis. The pyridoxal-5'-phosphate (PLP)-dependent l-serine hydroxymethyltransferase from Streptococcus thermophilus (SHMT Sth ; EC 2.1.2.1) was engineered to achieve the stereoselective synthesis of a broad structural variety of a,a-dialkyl-a-amino acids. This was accomplished by the formation of quaternary stereocenters through aldol addition of the amino acids d-Ala and d-Ser to a wide acceptor scope catalyzed by the minimalist SHMT Sth Y55T variant overcoming the limitation of the native enzyme for Gly. The SHMT Sth Y55T variant tolerates aromatic and aliphatic aldehydes as well as hydroxy-and nitrogen-containing aldehydes as acceptors.

Threonine aldolases: perspectives in engineering and screening the enzymes with enhanced substrate and stereo specificities

“…SHMT from Streptococcus thermophilus was engineered to catalyse the stereoselective synthesis of l -α-methyl- and α-hydroxymethyl-α-amino acids similar to published l TAs with broad donor specificity. The single mutation Y55T which was reported to be involved in the donor specificity increased the donor specificity towards d -serine, whereas only glycine and d -alanine (with less activity) were accepted by the wild-type enzyme (Hernandez et al 2015 ).…”

Asymmetric assembly of high-value α-functionalized organic acids using a biocatalytic chiral-group-resetting process

“…However, modern chemical C–H functionalization methods heavily rely on precious and unsustainable transition metals (e.g., Pd, Rh, Ru, and Ir) and protected substrates 12 – 14 . Hence, some researchers have turned to biocatalytic processes using some key enzymes such as threonine aldolases (TAs) 9 , 15 – 17 , which could catalyze the aldol assembly of unprotected small amino acids (principally glycine) and aldehydes to produce small organic acids, providing a dramatically simplified method. Another representative example is pyruvate aldolase, which uses alanine and formaldehyde as starting materials for the biosynthesis of ( S )- and ( R )-2-amino-4-hydroxybutanoic acid 9 .…”

“…Therefore, the assembly of small amino acids and aldehydes to form numerous α-keto acids and α-hydroxy acids is highly desired and remains a significant challenge. Fortunately, artificially designed multienzyme cascades, which offer a alternative to related chemical methods and protein engineering 3 , 11 , 17 , 20 , provide a useful tool for overcoming some challenging reactions 21 – 26 , such as the oxy- and amino-functionalization of alkenes 21 , 24 , 27 , 28 .…”

Reactor and microreactor performance and kinetics of the aldol addition of dihydroxyacetone to benzyloxycarbonyl-N-3-aminopropanal catalyzed by D-fructose-6-phosphate aldolase variant A129G

“…Aldolases are gaining a great interest in the synthesis of bioactive chiral carbohydrates, amino acids, etc. (Clap es and Joglar, 2013;Gu erard-H elaine et al, 2014;Soler et al, 2014;Hern andez et al, 2015;Szekrenyi et al, 2015;Rold an et al, 2017;Saravanan et al, 2017;Hern andez et al, 2018). This is due to their high efficiency, selectivity, and control over the configurations of the formed stereogenic centers.…”

“…Furthermore, they can operate under mild conditions and in aqueous solutions (M€ uller, 2012;M€ uller et al, 2013;Schmidt et al, 2016;Clap es, 2016aClap es, , 2016b. Another great advantage of using enzymes for C-C bond formation is their ability to form new C-C bonds with structurally different substrates as opposed to their natural substrates (Garrabou et al, 2009;Brovetto et al, 2011;Hern andez et al, 2015;Szekrenyi et al, 2015;G€ ucl€ u et al, 2016;Hern andez et al, 2017;Rold an et al, 2017;Saravanan et al, 2017;Hern andez et al, 2018). D-Fructose-6-phosphate aldolase from E. coli (FSA), first reported by Sch€ urmann and Sprenger (2001), catalyzes the equilibrium reaction between dihydroxyacetone (2) and aldehyde.…”