1f34: Difference between revisions

[[Image:1f34.gif|left|200px]]<br /><applet load="1f34" size="350" color="white" frame="true" align="right" spinBox="true"  

The three-dimensional structures of pepsin inhibitor-3 (PI-3) from Ascaris suum and of the complex between PI-3 and porcine pepsin at 1. 75 A and 2.45 A resolution, respectively, have revealed the mechanism of aspartic protease inhibition by this unique inhibitor. PI-3 has a new fold consisting of two domains, each comprising an antiparallel beta-sheet flanked by an alpha-helix. In the enzyme-inhibitor complex, the N-terminal beta-strand of PI-3 pairs with one strand of the 'active site flap' (residues 70-82) of pepsin, thus forming an eight-stranded beta-sheet that spans the two proteins. PI-3 has a novel mode of inhibition, using its N-terminal residues to occupy and therefore block the first three binding pockets in pepsin for substrate residues C-terminal to the scissile bond (S1'-S3'). The molecular structure of the pepsin-PI-3 complex suggests new avenues for the rational design of proteinaceous aspartic proteinase inhibitors.

1F34 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Ascaris_suum Ascaris suum] and [http://en.wikipedia.org/wiki/Sus_scrofa Sus scrofa] with <scene name='pdbligand=MPD:'>MPD</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Pepsin_A Pepsin A], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.23.1 3.4.23.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1F34 OCA].  

[[Category: Cherney, M M.]]

[[Category: James, M N.]]

[[Category: Ng, K K.]]

[[Category: Petersen, J F.]]

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