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PDBsum entry 2qa3

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protein ligands links
Transferase PDB id
2qa3
Jmol
Contents
Protein chain
385 a.a. *
Ligands
SO4 ×3
PSZ
PMP
GOL ×13
Waters ×407
* Residue conservation analysis
PDB id:
2qa3
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.
Resolution:
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
Date:
14-Jun-07     Release date:   04-Dec-07    
PROCHECK
Go to PROCHECK summary
 Headers
 References

Protein chain
Pfam   ArchSchema ?
P00509  (AAT_ECOLI) -  Aspartate aminotransferase
Seq:
Struc:
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.2.6.1.1  - Aspartate transaminase.
[IntEnz]   [ExPASy]   [KEGG]   [BRENDA]
      Reaction: L-aspartate + 2-oxoglutarate = oxaloacetate + L-glutamate
L-aspartate
+ 2-oxoglutarate
=
oxaloacetate
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  

 

 
    reference    
 
 
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.
 
  ABSTRACT  
 
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.