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Literature summary for 5.1.2.2 extracted from

  • Nagar, M.; Bearne, S.L.
    An additional role for the Broensted acid-base catalysts of mandelate racemase in transition state stabilization (2015), Biochemistry, 54, 6743-6752 .
    View publication on PubMed

Protein Variants

Protein Variants Comment Organism
H297N site-directed mutagenesis, analysis of ligand binding, kinetics Pseudomonas putida
K166C site-directed mutagenesis, analysis of ligand binding, kinetics Pseudomonas putida
K166M site-directed mutagenesis, analysis of ligand binding, kinetics Pseudomonas putida
K166M/H297N site-directed mutagenesis, analysis of ligand binding, kinetics Pseudomonas putida
additional information Comparison of the binding affinities of the mutant variants with the intermediate/transition state analogues benzohydroxamate and cyclohexanecarbohydroxamate reveals that cationPi/N-Pi interactions between His297 and the hydroxamate/hydroximate moiety and the phenyl ring of benzohydroxamate contribute approximately 0.26 and 0.91 kcal/mol to binding, respectively, while interactions with Lys166 contribute approximately 1.74 and 1.74 kcal/mol, respectively. Lys166 contributes over 2.93 kcal/mol to the binding of (R)-atrolactate, and His297 contributes 2.46 kcal/mol to the binding of (S)-atrolactate Pseudomonas putida

Inhibitors

Inhibitors Comment Organism Structure
benzohydroxamate BzH, the enzyme binds the intermediate/transition state analogue inhibitor in an entropy-driven process, consistent with an increased number of hydrophobic interactions, additional specific interactions contribute to binding, detailed kinetics and binding analysis, overview Pseudomonas putida

Organism

Organism UniProt Comment Textmining
Pseudomonas putida P11444
-
-

Reaction

Reaction Comment Organism Reaction ID
(S)-mandelate = (R)-mandelate the enzyme utilizes a two-base mechanism with Lys166 and His297 acting as Broensted acid and base catalysts, respectively, in the R -> S reaction direction. In the S -> R reaction direction, their roles are reversed Pseudomonas putida

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
(S)-atrolactate
-
Pseudomonas putida (R)-atrolactate
-
r
(S)-mandelate
-
Pseudomonas putida (R)-mandelate
-
r

General Information

General Information Comment Organism
additional information role for the Broensted acid-base catalysts of mandelate racemase in transition state stabilization. Enzyme-catalyzed abstraction of an alpha-proton from a carbon acid substrate with a high pKa. Residues Lys166 and His297 play dual roles in catalysis: they act as Broensted acid-base catalysts, and they stabilize both the enolate moiety and phenyl ring of the altered substrate in the transition state Pseudomonas putida
physiological function mandelate racemase catalyzes the interconversion of the enantiomers of mandelate Pseudomonas putida