1tju: Difference between revisions
No edit summary |
No edit summary |
||
| Line 1: | Line 1: | ||
[[Image:1tju.gif|left|200px]] | [[Image:1tju.gif|left|200px]] | ||
'''Crystal Structure of T161S Duck Delta 2 Crystallin Mutant''' | {{Structure | ||
|PDB= 1tju |SIZE=350|CAPTION= <scene name='initialview01'>1tju</scene>, resolution 2.10Å | |||
|SITE= | |||
|LIGAND= | |||
|ACTIVITY= [http://en.wikipedia.org/wiki/Argininosuccinate_lyase Argininosuccinate lyase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.3.2.1 4.3.2.1] | |||
|GENE= | |||
}} | |||
'''Crystal Structure of T161S Duck Delta 2 Crystallin Mutant''' | |||
==Overview== | ==Overview== | ||
| Line 7: | Line 16: | ||
==About this Structure== | ==About this Structure== | ||
1TJU is a [ | 1TJU is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Anas_platyrhynchos Anas platyrhynchos]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1TJU OCA]. | ||
==Reference== | ==Reference== | ||
Structural studies of duck delta2 crystallin mutants provide insight into the role of Thr161 and the 280s loop in catalysis., Sampaleanu LM, Codding PW, Lobsanov YD, Tsai M, Smith GD, Horvatin C, Howell PL, Biochem J. 2004 Dec 1;384(Pt 2):437-47. PMID:[http:// | Structural studies of duck delta2 crystallin mutants provide insight into the role of Thr161 and the 280s loop in catalysis., Sampaleanu LM, Codding PW, Lobsanov YD, Tsai M, Smith GD, Horvatin C, Howell PL, Biochem J. 2004 Dec 1;384(Pt 2):437-47. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/15320872 15320872] | ||
[[Category: Anas platyrhynchos]] | [[Category: Anas platyrhynchos]] | ||
[[Category: Argininosuccinate lyase]] | [[Category: Argininosuccinate lyase]] | ||
| Line 26: | Line 35: | ||
[[Category: eye lens protein]] | [[Category: eye lens protein]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 14:19:17 2008'' | ||
Revision as of 15:19, 20 March 2008
| |||||||
| , resolution 2.10Å | |||||||
|---|---|---|---|---|---|---|---|
| Activity: | Argininosuccinate lyase, with EC number 4.3.2.1 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Crystal Structure of T161S Duck Delta 2 Crystallin Mutant
OverviewOverview
Delta crystallin, a taxon-specific crystallin present in avian eye lenses, is homologous to the urea cycle enzyme ASL (argininosuccinate lyase). Although there are two delta crystallin isoforms in duck lenses, ddeltac1 (duck delta1 crystallin) and ddeltac2 (duck delta2 crystallin), only ddeltac2 is catalytically active. Previous structural studies have suggested that residues Ser283 and His162 in the multi-subunit active site of ddeltac2/ASL are the putative catalytic acid/base, while the highly conserved, positively charged Lys289 is thought to help stabilize the carbanion intermediate. The strict conservation of a small hydroxy-containing residue (Thr or Ser) at position 161 adjacent to the putative catalytic base, as well as its proximity to the substrate in the S283A ddeltac2 enzyme-substrate complex, prompted us to investigate further the role this residue. Structures of the active T161S and inactive T161D ddeltac2 mutants, as well as T161D complexed with argininosuccinate, have been determined to 2.0 A resolution. The structures suggest that a hydroxy group is required at position 161 to help correctly position the side chain of Lys289 and the fumarate moiety of the substrate. Threonine is probably favoured over serine, because the interaction of its methyl group with Leu206 would restrict its conformational flexibility. Residues larger than Thr or Ser interfere with substrate binding, supporting previous suggestions that correct positioning of the substrate's fumarate moiety is essential for catalysis to occur. The presence of the 280s loop (i.e. a loop formed by residues 270-290) in the 'open' conformation suggests that loop closure, thought to be essential for sequestration of the substrate, may be triggered by the formation of the carbanion or aci-carboxylate intermediates, whose charge distribution more closely mimics that of the sulphate ion found in the active-site region of the inactive ddeltac1. The 280s loop in ddeltac1 is in the closed conformation.
About this StructureAbout this Structure
1TJU is a Single protein structure of sequence from Anas platyrhynchos. Full crystallographic information is available from OCA.
ReferenceReference
Structural studies of duck delta2 crystallin mutants provide insight into the role of Thr161 and the 280s loop in catalysis., Sampaleanu LM, Codding PW, Lobsanov YD, Tsai M, Smith GD, Horvatin C, Howell PL, Biochem J. 2004 Dec 1;384(Pt 2):437-47. PMID:15320872
Page seeded by OCA on Thu Mar 20 14:19:17 2008