(S)-mandelate dehydrogenase;
MDH

Oxidoreductases;
Acting on the CH-OH group of donors;
With other acceptors

(S)-mandelate:acceptor 2-oxidoreductase

(S)-mandelate + acceptor = phenylglyoxylate + reduced acceptor [RN:R03793]

R03793 > R07664;
(other) R04160

(S)-mandelate [CPD:C01984];
acceptor [CPD:C00028]

This enzyme is a member of the FMN-dependent alpha-hydroxy-acid oxidase/dehydrogenase family [1]. While all enzymes of this family oxidize the (S)-enantiomer of an alpha-hydroxy acid to an alpha-oxo acid, the ultimate oxidant (oxygen, intramolecular heme or some other acceptor) depends on the particular enzyme. This enzyme transfers the electron pair from FMNH2 to a component of the electron transport chain, most probably ubiquinone [1,2]. It is part of a metabolic pathway in Pseudomonads that allows these organisms to utilize mandelic acid, derivatized from the common soil metabolite amygdalin, as the sole source of carbon and energy [2]. The enzyme has a large active-site pocket and preferentially binds substrates with longer sidechains, e.g. 2-hydroxyoctanoate rather than 2-hydroxybutyrate [1]. It also prefers substrates that, like (S)-mandelate, have beta unsaturation, e.g. (indol-3-yl)glycolate compared with (indol-3-yl)lactate [1]. Esters of mandelate, such as methyl (S)-mandelate, are also substrates [3].

1  [PMID:10231535]

Lehoux IE, Mitra B.

(S)-Mandelate dehydrogenase from Pseudomonas putida: mechanistic studies with alternate substrates and pH and kinetic isotope effects.

Biochemistry. 38 (1999) 5836-48.

Pseudomonas putida

2  [PMID:15311930]

Dewanti AR, Xu Y, Mitra B.

Role of glycine 81 in (S)-mandelate dehydrogenase from Pseudomonas putida in substrate specificity and oxidase activity.

Biochemistry. 43 (2004) 10692-700.

Pseudomonas putida

3  [PMID:14967029]

Dewanti AR, Xu Y, Mitra B.

Esters of mandelic acid as substrates for (S)-mandelate dehydrogenase from Pseudomonas putida: implications for the reaction mechanism.

Biochemistry. 43 (2004) 1883-90.

Pseudomonas putida