1rao: Difference between revisions

[[Image:1rao.gif|left|200px]]<br /><applet load="1rao" size="350" color="white" frame="true" align="right" spinBox="true"  

6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) catalyzes the Mg(2+)-dependent pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP). The reaction follows a bi-bi mechanism with ATP as the first substrate and AMP and HP pyrophosphate (HPPP) as the two products. HPPK is a key enzyme in the folate biosynthetic pathway and is essential for microorganisms but absent from mammals. For the HPPK-catalyzed pyrophosphoryl transfer, a reaction coordinate is constructed on the basis of the thermodynamic and transient kinetic data we reported previously, and the reaction trajectory is mapped out with five three-dimensional structures of the enzyme at various liganded states. The five structures are apo-HPPK (ligand-free enzyme), HPPK.MgATP(analog) (binary complex of HPPK with its first substrate) and HPPK.MgATP(analog).HP (ternary complex of HPPK with both substrates), which we reported previously, and HPPK.AMP.HPPP (ternary complex of HPPK with both product molecules) and HPPK.HPPP (binary complex of HPPK with one product), which we present in this study.

1RAO is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=AMP:'>AMP</scene> and <scene name='pdbligand=HH2:'>HH2</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/2-amino-4-hydroxy-6-hydroxymethyldihydropteridine_diphosphokinase 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine diphosphokinase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.6.3 2.7.6.3] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1RAO OCA].  

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:48:49 2008''