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| {{STRUCTURE_1mns| PDB=1mns | SCENE= }} | | {{STRUCTURE_1mns| PDB=1mns | SCENE= }} |
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| '''ON 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'''
| | ===ON 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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| ==Overview==
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| 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. | | The line below this paragraph, {{ABSTRACT_PUBMED_8292591}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 8292591 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_8292591}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Neidhart, D J.]] | | [[Category: Neidhart, D J.]] |
| [[Category: Racemase]] | | [[Category: Racemase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 01:28:37 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Jul 3 00:29:47 2008'' |