2qb2: Difference between revisions

Revision as of 19:37, 21 February 2008

Structural Studies Reveal the Inactivation of E. coli L-aspartate aminotransferase by (s)-4,5-dihydro-2thiophenecarboylic acid (SADTA) via two mechanisms (at pH 7.0).

OverviewOverview

As a mechanism-based inactivator of PLP-enzymes, (S)-4-amino-4,5-dihydro-2-thiophenecarboxylic acid (SADTA) was cocrystallized with Escherichia coli aspartate aminotransferase (l-AspAT) at a series of pH values ranging from 6 to 8. Five structural models with high resolution (1.4-1.85 A) were obtained for l-AspAT-SADTA complexes at pH 6.0, 6.5, 7.0, 7.5, and 8.0. Electron densities of the models showed that two different adducts had formed in the active sites. One adduct was formed from SADTA covalently linked to pyridoxal 5'-phosphate (PLP) while the other adduct was formed with the inhibitor covalently linked to Lysine246,1 the active site lysine. Moreover, there is a strong indication based on the electron densities that the occurrence of the two adducts is pH dependent. We conclude that SADTA inactivates l-AspAT via two different mechanisms based on the binding direction of the inactivator. Additionally, the structural models also show pH dependence of the protein structure itself, which provided detailed mechanistic implications for l-AspAT.

About this StructureAbout this Structure

2QB2 is a Single protein structure of sequence from Escherichia coli with , , and as ligands. Active as Aspartate transaminase, with EC number 2.6.1.1 Full crystallographic information is available from OCA.

ReferenceReference

Inactivation of Escherichia coli L-aspartate aminotransferase by (S)-4-amino-4,5-dihydro-2-thiophenecarboxylic acid reveals "a tale of two mechanisms"., Liu D, Pozharski E, Lepore BW, Fu M, Silverman RB, Petsko GA, Ringe D, Biochemistry. 2007 Sep 18;46(37):10517-27. Epub 2007 Aug 22. PMID:17713924

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 ==Overview==
-As a mechanism-based inactivator of PLP-enzymes, (S)-4-amino-4,5-dihydro-2-thiophenecarboxylic acid (SADTA) was, cocrystallized with Escherichia coli aspartate aminotransferase (l-AspAT), at a series of pH values ranging from 6 to 8. Five structural models with, high resolution (1.4-1.85 A) were obtained for l-AspAT-SADTA complexes at, pH 6.0, 6.5, 7.0, 7.5, and 8.0. Electron densities of the models showed, that two different adducts had formed in the active sites. One adduct was, formed from SADTA covalently linked to pyridoxal 5'-phosphate (PLP) while, the other adduct was formed with the inhibitor covalently linked to, Lysine246,1 the active site lysine. Moreover, there is a strong indication, based on the electron densities that the occurrence of the two adducts is, pH dependent. We conclude that SADTA inactivates l-AspAT via two different, mechanisms based on the binding direction of the inactivator., Additionally, the structural models also show pH dependence of the protein, structure itself, which provided detailed mechanistic implications for, l-AspAT.
+As a mechanism-based inactivator of PLP-enzymes, (S)-4-amino-4,5-dihydro-2-thiophenecarboxylic acid (SADTA) was cocrystallized with Escherichia coli aspartate aminotransferase (l-AspAT) at a series of pH values ranging from 6 to 8. Five structural models with high resolution (1.4-1.85 A) were obtained for l-AspAT-SADTA complexes at pH 6.0, 6.5, 7.0, 7.5, and 8.0. Electron densities of the models showed that two different adducts had formed in the active sites. One adduct was formed from SADTA covalently linked to pyridoxal 5'-phosphate (PLP) while the other adduct was formed with the inhibitor covalently linked to Lysine246,1 the active site lysine. Moreover, there is a strong indication based on the electron densities that the occurrence of the two adducts is pH dependent. We conclude that SADTA inactivates l-AspAT via two different mechanisms based on the binding direction of the inactivator. Additionally, the structural models also show pH dependence of the protein structure itself, which provided detailed mechanistic implications for l-AspAT.
 ==About this Structure==
@@ Line 10: / Line 10: @@
 ==Reference==
-Inactivation of Escherichia coli l-Aspartate Aminotransferase by (S)-4-Amino-4,5-dihydro-2-thiophenecarboxylic Acid Reveals "A Tale of Two Mechanisms"(,)., Liu D, Pozharski E, Lepore BW, Fu M, Silverman RB, Petsko GA, Ringe D, Biochemistry. 2007 Aug 22;. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17713924 17713924]
+Inactivation of Escherichia coli L-aspartate aminotransferase by (S)-4-amino-4,5-dihydro-2-thiophenecarboxylic acid reveals "a tale of two mechanisms"., Liu D, Pozharski E, Lepore BW, Fu M, Silverman RB, Petsko GA, Ringe D, Biochemistry. 2007 Sep 18;46(37):10517-27. Epub 2007 Aug 22. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17713924 17713924]
 [[Category: Aspartate transaminase]]
 [[Category: Escherichia coli]]
@@ Line 17: / Line 17: @@
 [[Category: Lepore, B.]]
 [[Category: Liu, D.]]
-[[Category: Petsko, G.A.]]
+[[Category: Petsko, G A.]]
 [[Category: Pozharski, E.]]
 [[Category: Ringe, D.]]
-[[Category: Silverman, R.B.]]
+[[Category: Silverman, R B.]]
 [[Category: GOL]]
 [[Category: PMP]]
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 [[Category: sadta]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jan 23 11:52:02 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 18:37:51 2008''