1mdr
THE ROLE OF LYSINE 166 IN THE MECHANISM OF MANDELATE RACEMASE FROM PSEUDOMONAS PUTIDA: MECHANISTIC AND CRYSTALLOGRAPHIC EVIDENCE FOR STEREOSPECIFIC ALKYLATION BY (R)-ALPHA-PHENYLGLYCIDATE
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| , resolution 2.1Å | |||||||
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| Ligands: | and | ||||||
| Activity: | Mandelate racemase, with EC number 5.1.2.2 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
OverviewOverview
The mechanism of irreversible inactivation of mandelate racemase (MR) from Pseudomonas putida by alpha-phenylglycidate (alpha PGA) has been investigated stereochemically and crystallographically. The (R) and (S) enantiomers of alpha PGA were synthesized in high enantiomeric excess (81% ee and 83% ee, respectively) using Sharpless epoxidation chemistry. (R)-alpha PGA was determined to be a stereospecific and stoichiometric irreversible inactivator of MR. (S)-alpha PGA does not inactivate MR and appears to bind noncovalently to the active site of MR with less affinity than that of (R)-alpha PGA. The X-ray crystal structure (2.0-A resolution) of MR inactivated by (R)-alpha PGA revealed the presence of a covalent adduct formed by nucleophilic attack of the epsilon-amino group of Lys 166 on the distal carbon on the epoxide ring of (R)-alpha PGA. The proximity of the alpha-proton of (S)-mandelate to Lys 166 [configurationally equivalent to (R)-alpha PGA] was corroborated by the crystal structure (2.1-A resolution) of MR complexed with the substrate analog/competitive inhibitor, (S)-atrolactate [(S)-alpha-methylmandelate]. These results support the proposal that Lys 166 is the polyvalent acid/base responsible for proton transfers on the (S) face of mandelate. In addition, the high-resolution structures also provide insight into the probable interactions of mandelate with the essential Mg2+ and functional groups in the active site.
About this StructureAbout this Structure
1MDR is a Single protein structure of sequence from Pseudomonas putida. Full crystallographic information is available from OCA.
ReferenceReference
The role of lysine 166 in the mechanism of mandelate racemase from Pseudomonas putida: mechanistic and crystallographic evidence for stereospecific alkylation by (R)-alpha-phenylglycidate., Landro JA, Gerlt JA, Kozarich JW, Koo CW, Shah VJ, Kenyon GL, Neidhart DJ, Fujita S, Petsko GA, Biochemistry. 1994 Jan 25;33(3):635-43. PMID:8292591
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