1n5d: Difference between revisions

[[Image:1n5d.gif|left|200px]]<br /><applet load="1n5d" size="350" color="white" frame="true" align="right" spinBox="true"  

Porcine testicular carbonyl reductase (PTCR) belongs to the short chain dehydrogenases/reductases (SDR) superfamily and catalyzes the NADPH-dependent reduction of ketones on steroids and prostaglandins. The enzyme shares nearly 85% sequence identity with the NADPH-dependent human 15-hydroxyprostaglandin dehydrogenase/carbonyl reductase. The tertiary structure of the enzyme at 2.3 A reveals a fold characteristic of the SDR superfamily that uses a Tyr-Lys-Ser triad as catalytic residues, but exhibits neither the functional homotetramer nor the homodimer that distinguish all SDRs. It is the first known monomeric structure in the SDR superfamily. In PTCR, which is also active as a monomer, a 41-residue insertion immediately before the catalytic Tyr describes an all-helix subdomain that packs against interfacial helices, eliminating the four-helix bundle interface conserved in the superfamily. An additional anti-parallel strand in the PTCR structure also blocks the other strand-mediated interface. These novel structural features provide the basis for the scaffolding of one catalytic site within a single molecule of the enzyme.

1N5D is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Sus_scrofa Sus scrofa] with <scene name='pdbligand=SO4:'>SO4</scene> and <scene name='pdbligand=NDP:'>NDP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. This structure supersedes the now removed PDB entry 1HU4. Active as [http://en.wikipedia.org/wiki/3-alpha-(or_20-beta)-hydroxysteroid_dehydrogenase 3-alpha-(or 20-beta)-hydroxysteroid dehydrogenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.53 1.1.1.53] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1N5D OCA].  

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