1u0f: Difference between revisions

[[Image:1u0f.jpg|left|200px]]<br /><applet load="1u0f" size="350" color="white" frame="true" align="right" spinBox="true"  

Phosphoglucose isomerase (PGI) is an enzyme of glycolysis that interconverts glucose 6-phosphate (G6P) and fructose 6-phosphate (F6P) but, outside the cell, is a multifunctional cytokine. High-resolution crystal structures of the enzyme from mouse have been determined in native form and in complex with the inhibitor erythrose 4-phosphate, and with the substrate glucose 6-phosphate. In the substrate-bound structure, the glucose sugar is observed in both straight-chain and ring forms. This structure supports a specific role for Lys518 in enzyme-catalyzed ring opening and we present a "push-pull" mechanism in which His388 breaks the O5-C1 bond by donating a proton to the ring oxygen atom and, simultaneously, Lys518 abstracts a proton from the C1 hydroxyl group. The reverse occurs in ring closure. The transition from ring form to straight-chain substrate is achieved through rotation of the C3-C4 bond, which brings the C1-C2 region into close proximity to Glu357, the base catalyst for the isomerization step. The structure with G6P also explains the specificity of PGI for glucose 6-phosphate over mannose 6-isomerase (M6P). To isomerize M6P to F6P requires a rotation of its C2-C3 bond but in PGI this is sterically blocked by Gln511.

1U0F is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus] with <scene name='pdbligand=G6P:'>G6P</scene>, <scene name='pdbligand=G6Q:'>G6Q</scene>, <scene name='pdbligand=SO4:'>SO4</scene>, <scene name='pdbligand=BME:'>BME</scene> and <scene name='pdbligand=GOL:'>GOL</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Glucose-6-phosphate_isomerase Glucose-6-phosphate isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.1.9 5.3.1.9] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1U0F OCA].  

[[Category: Solomons, J T.G.]]

[[Category: Swan, M K.]]

[[Category: Zimmerly, E M.]]

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