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1.1.1.379

Accepted name:

(R)-mandelate dehydrogenase

Reaction:

(R)-mandelate + NAD⁺ = phenylglyoxylate + NADH + H⁺

Glossary:

(R)-mandelate = D-mandelate

Other name(s):

ManDH₂; D-ManDH₂; D-mandelate dehydrogenase (ambiguous)

Systematic name:

(R)-mandelate:NAD⁺ 2-oxidoreductase

Comments:

The enzyme, found in bacteria and fungi, can also accept a number of substituted mandelate derivatives, such as 3-hydroxymandelate, 4-hydroxymandelate, 2-methoxymandelate, 4-hydroxy-3-methoxymandelate and 3-hydroxy-4-methoxymandelate. The enzyme has no activity with (S)-mandelate (cf. EC 1.1.99.31, (S)-mandelate dehydrogenase) [1,2]. The enzyme transfers the pro-R-hydrogen from NADH [2].

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc

References:

1.	Baker, D.P. and Fewson, C.A. Purification and characterization of D(–)-mandelate dehydrogenase from Rhodotorula graminis. Microbiology 135 (1989) 2035–2044.
2.	Baker, D.P., Kleanthous, C., Keen, J.N., Weinhold, E. and Fewson, C.A. Mechanistic and active-site studies on D(–)-mandelate dehydrogenase from Rhodotorula graminis. Biochem. J. 281 (1992) 211–218. [PMID: 1731758]

[EC 1.1.1.379 created 2014]

1.1.99.31

Accepted name:

(S)-mandelate dehydrogenase

Reaction:

(S)-mandelate + acceptor = phenylglyoxylate + reduced acceptor

For diagram of reaction, click here

Glossary:

(S)-mandelate = (S)-2-hydroxy-2-phenylacetate
phenylglyoxylate = benzoylformate = 2-oxo-2-phenylacetate

Other name(s):

MDH (ambiguous)

Systematic name:

(S)-mandelate:acceptor 2-oxidoreductase

Comments:

This enzyme is a member of the FMN-dependent α-hydroxy-acid oxidase/dehydrogenase family [1]. While all enzymes of this family oxidize the (S)-enantiomer of an α-hydroxy acid to an α-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 β 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].

Links to other databases:

BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9067-95-2

References:

1.	Lehoux, I.E. and Mitra, B. (S)-Mandelate dehydrogenase from Pseudomonas putida: mechanistic studies with alternate substrates and pH and kinetic isotope effects. Biochemistry 38 (1999) 5836–5848. [DOI] [PMID: 10231535]
2.	Dewanti, A.R., Xu, Y. and Mitra, B. Role of glycine 81 in (S)-mandelate dehydrogenase from Pseudomonas putida in substrate specificity and oxidase activity. Biochemistry 43 (2004) 10692–10700. [DOI] [PMID: 15311930]
3.	Dewanti, A.R., Xu, Y. and Mitra, B. Esters of mandelic acid as substrates for (S)-mandelate dehydrogenase from Pseudomonas putida: implications for the reaction mechanism. Biochemistry 43 (2004) 1883–1890. [DOI] [PMID: 14967029]

[EC 1.1.99.31 created 2006]

5.1.2.2

Accepted name:

mandelate racemase

Reaction:

(S)-mandelate = (R)-mandelate

Glossary:

mandelate = 2-hydroxy-2-phenylacetate

Systematic name:

mandelate racemase

Links to other databases:

BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9024-04-8

References:

1.	Gunsalus, C.F., Stanier, R.Y. and Gunsalus, I.C. The enzymatic conversion of mandelic acid to benzoic acid. III. Fractionation and properties of the soluble enzymes. J. Bacteriol. 66 (1953) 548–553. [PMID: 13108854]

[EC 5.1.2.2 created 1961]