PDBsum entry 2qa3

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protein ligands links
Transferase PDB id
Protein chain
385 a.a. *
SO4 ×3
GOL ×13
Waters ×407
* Residue conservation analysis
PDB id:
Name: Transferase
Title: Structural studies reveal the inactivation of e. Coli l-aspa aminotransferase by (s)-4,5-amino-dihydro-2-thiophenecarbox (sadta) via two mechanisms (at ph6.5)
Structure: Aspartate aminotransferase. Chain: a. Synonym: transaminase a, aspat. Engineered: yes
Source: Escherichia coli. Organism_taxid: 562. Gene: aspc. Expressed in: escherichia coli. Expression_system_taxid: 562.
1.75Å     R-factor:   0.157     R-free:   0.197
Authors: D.Liu,E.Pozharski,B.Lepore,M.Fu,R.B.Silverman,G.A.Petsko,D.R
Key ref: D.Liu et al. (2007). Inactivation of Escherichia coli L-aspartate aminotransferase by (S)-4-amino-4,5-dihydro-2-thiophenecarboxylic acid reveals "a tale of two mechanisms". Biochemistry, 46, 10517-10527. PubMed id: 17713924 DOI: 10.1021/bi700663n
14-Jun-07     Release date:   04-Dec-07    
Go to PROCHECK summary

Protein chain
Pfam   ArchSchema ?
P00509  (AAT_ECOLI) -  Aspartate aminotransferase
396 a.a.
385 a.a.*
Key:    PfamA domain  Secondary structure  CATH domain
* PDB and UniProt seqs differ at 1 residue position (black cross)

 Enzyme reactions 
   Enzyme class: E.C.  - Aspartate transaminase.
[IntEnz]   [ExPASy]   [KEGG]   [BRENDA]
      Reaction: L-aspartate + 2-oxoglutarate = oxaloacetate + L-glutamate
+ 2-oxoglutarate
Bound ligand (Het Group name = GOL)
matches with 50.00% similarity
+ L-glutamate
      Cofactor: Pyridoxal 5'-phosphate
Pyridoxal 5'-phosphate
Bound ligand (Het Group name = PSZ) matches with 60.00% similarity
Molecule diagrams generated from .mol files obtained from the KEGG ftp site
 Gene Ontology (GO) functional annotation 
  GO annot!
  Cellular component     cytoplasm   2 terms 
  Biological process     biosynthetic process   4 terms 
  Biochemical function     catalytic activity     8 terms  


DOI no: 10.1021/bi700663n Biochemistry 46:10517-10527 (2007)
PubMed id: 17713924  
Inactivation of Escherichia coli L-aspartate aminotransferase by (S)-4-amino-4,5-dihydro-2-thiophenecarboxylic acid reveals "a tale of two mechanisms".
D.Liu, E.Pozharski, B.W.Lepore, M.Fu, R.B.Silverman, G.A.Petsko, D.Ringe.
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.