View source for 1hg0

[[Image:1hg0.gif|left|200px]]

 {{Structure
|PDB= 1hg0 |SIZE=350|CAPTION= <scene name='initialview01'>1hg0</scene>, resolution 1.90&Aring;
|SITE= <scene name='pdbsite=AS1:Active+Site+Chain+A'>AS1</scene>, <scene name='pdbsite=AS2:Active+Site+Chain+B'>AS2</scene>, <scene name='pdbsite=AS3:Active+Site+Chain+C'>AS3</scene>, <scene name='pdbsite=AS4:Active+Site+Chain+D'>AS4</scene>, <scene name='pdbsite=LI1:Sin+Binding+Site+For+Chain+A'>LI1</scene>, <scene name='pdbsite=LI2:Sin+Binding+Site+For+Chain+B'>LI2</scene>, <scene name='pdbsite=LI3:Sin+Binding+Site+For+Chain+C'>LI3</scene> and <scene name='pdbsite=LI4:Sin+Binding+Site+For+Chain+D'>LI4</scene>
|LIGAND= <scene name='pdbligand=SIN:SUCCINIC ACID'>SIN</scene>
|ACTIVITY= [http://en.wikipedia.org/wiki/Asparaginase Asparaginase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.1.1 3.5.1.1] 
|GENE= 
}}

'''X-RAY STRUCTURE OF THE COMPLEX BETWEEN ERWINIA CHRYSANTHEMI L-ASPARAGINASE AND SUCCINIC ACID'''


==Overview==
Bacterial L-asparaginases, enzymes that catalyze the hydrolysis of L-asparagine to aspartic acid, have been used for over 30 years as therapeutic agents in the treatment of acute childhood lymphoblastic leukemia. Other substrates of asparaginases include L-glutamine, D-asparagine, and succinic acid monoamide. In this report, we present high-resolution crystal structures of the complexes of Erwinia chrysanthemi L-asparaginase (ErA) with the products of such reactions that also can serve as substrates, namely L-glutamic acid (L-Glu), D-aspartic acid (D-Asp), and succinic acid (Suc). Comparison of the four independent active sites within each complex indicates unique and specific binding of the ligand molecules; the mode of binding is also similar between complexes. The lack of the alpha-NH3(+) group in Suc, compared to L-Asp, does not affect the binding mode. The side chain of L-Glu, larger than that of L-Asp, causes several structural distortions in the ErA active side. The active site flexible loop (residues 15-33) does not exhibit stable conformation, resulting in suboptimal orientation of the nucleophile, Thr15. Additionally, the delta-COO(-) plane of L-Glu is approximately perpendicular to the plane of gamma-COO(-) in L-Asp bound to the asparaginase active site. Binding of D-Asp to the ErA active site is very distinctive compared to the other ligands, suggesting that the low activity of ErA against D-Asp could be mainly attributed to the low k(cat) value. A comparison of the amino acid sequence and the crystal structure of ErA with those of other bacterial L-asparaginases shows that the presence of two active-site residues, Glu63(ErA) and Ser254(ErA), may correlate with significant glutaminase activity, while their substitution by Gln and Asn, respectively, may lead to minimal L-glutaminase activity.

==About this Structure==
1HG0 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Erwinia_chrysanthemi Erwinia chrysanthemi]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1HG0 OCA]. 

==Reference==
Structural basis for the activity and substrate specificity of Erwinia chrysanthemi L-asparaginase., Aghaiypour K, Wlodawer A, Lubkowski J, Biochemistry. 2001 May 15;40(19):5655-64. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/11341830 11341830]
[[Category: Asparaginase]]
[[Category: Erwinia chrysanthemi]]
[[Category: Single protein]]
[[Category: Kolyani, K A.]]
[[Category: Lubkowski, J.]]
[[Category: Wlodawer, A.]]
[[Category: SIN]]
[[Category: asparaginase]]
[[Category: complex]]
[[Category: d-aspartate]]
[[Category: hydrolase]]
[[Category: structure]]
[[Category: x-ray]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 11:36:39 2008''