1fyd: Difference between revisions

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

The NH(3)-dependent NAD(+) synthetase (NADS) participates in the biosynthesis of nicotinamide adenine dinucleotide (NAD(+)) by transforming nicotinic acid adenine dinucleotide (NaAD) to NAD(+). The structural behavior of the active site, including stabilization of flexible loops 82-87 and 204-225, has been studied by determination of the crystal structures of complexes of NADS with natural substrates and a substrate analog. Both loops are stabilized independently of NaAD and solely from the ATP-binding site. Analysis of the binding contacts suggests that the minor loop 82-87 is stabilized primarily by a hydrogen bond with the adenine base of ATP. Formation of a coordination complex with Mg(2+) in the ATP-binding site may contribute to the stabilization of the major loop 204-225. The major loop has a role in substrate recognition and stabilization, in addition to the protection of the reaction intermediate described previously. A second and novel Mg(2+) position has been observed closer to the NaAD-binding site in the structure crystallized at pH 7.5, where the enzyme is active. This could therefore be the catalytically active Mg(2+).

1FYD is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_subtilis Bacillus subtilis] with <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=AMP:'>AMP</scene> and <scene name='pdbligand=POP:'>POP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/NAD(+)_synthase_(glutamine-hydrolyzing) NAD(+) synthase (glutamine-hydrolyzing)], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.3.5.1 6.3.5.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1FYD OCA].  

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