Microbial Production of Optically Active β-Phenylalanine through Stereoselective Degradation of Racemic β-Phenylalanine

Enantiomer discrimination in β-phenylalanine degradation by a newly isolated Paraburkholderia strain BS115 and type strain PsJN

“…Deracemization of β-PA by living cells has only once been reported so far: The only comparable fermentation example from Mano et al showed that the soil bacterium Variovorax sp. JH2 is able to convert ( S )-selective 61 mM of β-PA within 8 days (Mano et al 2006 ). They achieved a maximal degradation rate of 0.26 mM/h towards ( S )-β-PA, which is comparable to the uptake rates of PsJN and BS115.…”

“…AKU 638, which is suitable for chiral resolution to gain the optical pure ( S )-β-PA. However, this degradation process is very slow and took 13 days of fermentation and in contrast to BS115 they did not recognize any depletion of the ( S )-enantiomer at the same time (Mano et al 2006 ). Oxidative deamination has been suggested, but until now, the mechanism for the degradation of ( R )-β-PA in Arthrobacter sp.…”

“…Transamination was found to be the predominant initial degradation step in all isolated bacteria: biotransformation with cell-free extracts and fractions thereof was only observed when a suitable amino acceptor was additionally applied (preferably α-ketoglutarate or pyruvate) as well as the well-known transaminase cofactor pyridoxal phosphate (PLP). The fermentative degradation of rac -β-PA by living cells has only once been documented by Mano et al in ( 2006 ). The ( S )-selective ω-TA involved in this degradation has been characterized in detail by Hibi et al ( 2012 ).…”

Transaminases for the synthesis of enantiopure beta-amino acids

“…Taking into consideration sequences which were submitted to Genbank since the publication of this article, the comparison of this amino acid sequence using blastp gives a putative aminotransferase class III from Variovorax paradoxus S110 (Gene ID: :7970445) as the closest match with 52% identities and 69% similarity. Interestingly, of the other transaminases reported to act on β-phenylalanine, one belongs to the species V. paradoxus (Banerjee et al 2005) and two to the genus Variovorax (Brucher et al 2010Mano et al 2006). The preliminary X-ray structure of the TA from Mesorhizobium sp.…”

An efficient new enzymatic method for the preparation of β-aryl-β-amino acid enantiomers

“…1 There are several methods for the synthesis of enantiopure b-aryl-b-amino acids, such as (i) the enantioselective reduction of a b-enamino ester; 2 (ii) the addition of a chiral sulfoxide to a substituted N-sulfonylimine; 3 (iii) an asymmetric catalytic Mannich reaction; 4 (iv) the conjugate addition of a chiral lithium amide to a b-aryl a,b-unsaturated ester; 5 (v) the reaction of a Reformatsky reagent with an imine; 6 or (vi) the preparation of a diastereomeric salt. 7 In addition to asymmetric synthetic routes, 2-7 enzyme-catalysed processes have been developed through (i) the transesterification of an N-protected ester in isobutanol; 8 (ii) stereoselective degradation of a racemic amino acid; 9 (iii) hydrolysis of a racemic b-amino ester; 10 (iv) hydrolysis of a racemic N-acetylated b-amino acid; 11 or (v) an aminomutasecatalysed a,b-rearrangement 12 in aqueous medium.…”