1p6d: Difference between revisions

[[Image:1p6d.jpg|left|200px]]<br /><applet load="1p6d" size="350" color="white" frame="true" align="right" spinBox="true"  

Because mutations of the ionizable Asp at position 55 of the phosphatidylcholine preferring phospholipase C from Bacillus cereus (PLC(Bc)) to a non-ionizable Asn generate a mutant enzyme (D55N) with 10(4)-fold lower catalytic activity than the wild-type enzyme, we tentatively identified Asp55 as the general base for the enzymatic reaction. To eliminate the alternate possibility that Asp55 is a structurally important amino acid, the X-ray structures of unbound D55N and complexes of D55N with two non-hydrolyzable substrate analogues have been solved and refined to 2.0, 2.0, and 2.3A, respectively. The structures of unbound wild-type PLC(Bc) and a wild-type PLC(Bc)-complex with a non-hydrolyzable substrate analogue do not change significantly as a result of replacing Asp55 with Asn. These observations demonstrate that Asp55 is not critical for the structural integrity of the enzyme and support the hypothesis that Asp55 is the general base in the PLC(Bc)-catalyzed hydrolysis of phospholipids.

1P6D is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_cereus Bacillus cereus] with <scene name='pdbligand=ZN:'>ZN</scene> and <scene name='pdbligand=3PC:'>3PC</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Phospholipase_C Phospholipase C], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.4.3 3.1.4.3] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1P6D OCA].  

[[Category: Antikainen, N M.]]

[[Category: Franklin, C L.]]

[[Category: Martin, S F.]]

[[Category: Monzingo, A F.]]

[[Category: Robertus, J D.]]

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