2skd: Difference between revisions

[[Image:2skd.gif|left|200px]]<br /><applet load="2skd" size="350" color="white" frame="true" align="right" spinBox="true"  

It has been established that phosphate analogues can activate glycogen phosphorylase reconstituted with pyridoxal in place of the natural cofactor pyridoxal 5'-phosphate (Change YC. McCalmont T, Graves DJ. 1983. Biochemistry 22:4987-4993). Pyridoxal phosphorylase b has been studied by kinetic, ultracentrifugation, and X-ray crystallographic experiments. In solution, the catalytically active species of pyridoxal phosphorylase b adopts a conformation that is more R-state-like than that of native phosphorylase b, but an inactive dimeric species of the enzyme can be stabilized by activator phosphite in combination with the T-state inhibitor glucose. Co-crystals of pyridoxal phosphorylase b complexed with either phosphite, phosphate, or fluorophosphate, the inhibitor glucose, and the weak activator IMP were grown in space group P4(3)2(1)2, with native-like unit cell dimensions, and the structures of the complexes have been refined to give crystallographic R factors of 18.5-19.2%, for data between 8 and 2.4 A resolution. The anions bind tightly at the catalytic site in a similar but not identical position to that occupied by the cofactor 5'-phosphate group in the native enzyme (phosphorus to phosphorus atoms distance = 1.2 A). The structural results show that the structures of the pyridoxal phosphorylase b-anion-glucose-IMP complexes are overall similar to the glucose complex of native T-state phosphorylase b. Structural comparisons suggest that the bound anions, in the position observed in the crystal, might have a structural role for effective catalysis.

2SKD is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Oryctolagus_cuniculus Oryctolagus cuniculus] with <scene name='pdbligand=GLC:'>GLC</scene>, <scene name='pdbligand=PO4:'>PO4</scene>, <scene name='pdbligand=PLP:'>PLP</scene> and <scene name='pdbligand=IMP:'>IMP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. This structure supersedes the now removed PDB entry 1SKD. Active as [http://en.wikipedia.org/wiki/Phosphorylase Phosphorylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.1.1 2.4.1.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2SKD OCA].  

[[Category: Acharya, K R.]]

[[Category: Johnson, L N.]]

[[Category: Oikonomakos, N G.]]

[[Category: Tsitsanou, K E.]]

[[Category: Zographos, S E.]]

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