Mandelate dehydrogenase

Tsou AY, SC Ransom, JA Gerlt, DD Buechter, PC Babbitt, GL Kenyon (1990) Mandelate pathway of Pseudomonas putida sequence relationships involving mandelate racemase, (5)-mandelate dehydrogenase, and benzoylformate decarboxylase and expression of benzoylformate decarboxylase in Escherichia coli. Biochemistry 29 9856-9862. 

The present reaction was proven to occur even when the microorganism had been grown on peptone as the sole carbon source. These results lead to the conclusion that this enzyme system is produced constitutively. In the case of man-delate-pathway enzymes in Pseudomonas putida, (S)-mandelate dehydrogenase was shown to be produced in the presence of an inducer (mandelic acid or benzoylformic acid) [5]. Thus, the expression of the present oxidizing enzyme of A. bronchisepticus is different from that of R putida. 

As all enzymes of the mandelate path are located on one operon, the other four enzymes could also be identified, cloned, and sequenced. (S)-Mandelate dehydrogenase [(S)-ManDH] features similarities to glycolate oxidase and flavocyto-chrome b2 (a lactate-DH) both are a/f-barrel proteins and require FMN as cofactor as does (S)-ManDH. It is reasonable to conclude that in this case nature has also sequestered a template that already catalyzes a chemistry similar to the desired reaction. 

Enzyme-catalyzed syntheses of enantiomeric pure hydroxy acids use lactate dehydrogenases (LDH E.C. 1.1.1.27) or hydroxyisocaproate dehydrogenases (HicDH). Both kinds of enzymes are available as D- or L-specific catalysts. L-specific [5, 6] LDHs as well as D-specific [7-10] LDHs favorably catalyze the reduction of pyruvate, HicDHs (and mandelate dehydrogenase, too) convert keto acids with longer aliphatic or aromatic side chains. These enzymes can be isolated from Lactobacillus strains [11-14]. 

Flavocytochromes 2 2-hydroxyacid dehydrogenases found in the inter-membrane space of yeast mitochondria where they couple oxidation of the substrate to reduction of cytochrome c. Examples include the enzymes from Saccharomyces cerevisiae and Hansenula anomala, both of which are l-lactate dehydrogenases (Chapman et al., 1998), and the enzyme from Rhodotorula graminis which is a L-mandelate dehydrogenase (Ilias et al., 1998). This article will concentrate on the flavocytochrome 2 (L-lactate cytochrome c oxidoreductase) from S. cerevisiae (Bakersi yeast), since this is by far the most studied of these enzymes (Chapman et al., 1991). Therefore, throughout this article, the term flavocytochrome 2 will refer specifically to the enzyme from S. cerevisiae unless otherwise stated. 

Sinclair, R. Reid, G., and Chapman, S. K., 1998, Re-design of Saccharomyces cerevisiae flavocytochrome fcj introduction of L-mandelate dehydrogenase activity, Biochem. J. 333 117nl20. 

Both enantiomers of mandelate were degraded through the activity of a mandelate racemase (Hegeman 1966), and the racemase (mdlA) is encoded in an operon that includes the following two enzymes in the pathway of degradation, S-mandelate dehydrogenase (mdlB) and benzoylformate decarboxylase (mdlC) (Tsou et al. 1990). 

This reaction has recently been improved by the use of isolated mandelate dehydrogenase from Lactobacillus curvatus314 or Streptococcus faecalis315 in a membrane reactor. 

Fig. 6.4.2 Asymmetric reductions catalyzed by mandelate dehydrogenase and alcohol...

Magnetic Fe304—chitosan NPs Adsorption of Saccharomyces cerevisiae mandelated dehydrogenase [230]... 

Li GY, Jiang YR, Huang KL, Ding P, Yao LL. Kinetics of adsorption of Saccharomyces cere-visiae mandelated dehydrogenase on magnetic Fe304-chitosan nanoparticles. Colloids Surf A Physicochem Eng Asp. 2008 320(l-3) ll-8. 

More recently, the focus has been put on formal nucleophilic substitution of —OH or —NH2 groups. To perform this biocatalytic variant of the Mitsunobu reaction, an oxidation-nucleophilic addition-reduction sequence is necessary, for which linked NAD-dependent oxidoreductases are ideally suited. The early contributions from the Forschungszentrum Jiilich [79] have been recently rediscovered by Kroutil and coworkers [80]. By combining a mandelate racemase (MR) with a mandelate dehydrogenase and an L-amino acid dehydrogenase, the authors could completely transform racemic mandelic acid into enantiopure (S)-phenyl-glycine (Scheme 8.16). 

Scheme 8.16 Formal Mitsunobu reaction by combining an alcohol dehydrogenase (here mandelate dehydrogenase, D-MDH) with an amino acid dehydrogenase (here l-AADH).

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