1dbr | pdb_00001dbr
HYPOXANTHINE GUANINE XANTHINE
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Overview
Crystal structures of substrate-free and XMP-soaked hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRTase) of the opportunistic pathogen Toxoplasma gondii have been determined to 2.4 and 2.9 A resolution, respectively. HGXPRTase displays the conserved PRTase fold. In the structure of the enzyme bound to its product, a long flexible loop (residues 115-126) is located away from the active site. Comparison to the substrate-free structure reveals a striking relocation of the loop, which is poised to cover the catalytic pocket, thus providing a mechanism by which the HG(X)PRTases shield their oxocarbonium transition states from nucleophilic attack by the bulk solvent. The conserved Ser 117-Tyr 118 dipeptide within the loop is brought to the active site, completing the ensemble of catalytic residues.
About this Structure
1DBR is a Single protein structure of sequence from Toxoplasma gondii with MG as ligand. Full crystallographic information is available from OCA.
Reference
Crystal structures of Toxoplasma gondii HGXPRTase reveal the catalytic role of a long flexible loop., Schumacher MA, Carter D, Ross DS, Ullman B, Brennan RG, Nat Struct Biol. 1996 Oct;3(10):881-7. PMID:8836106
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