3er5
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(New page: 200px<br /><applet load="3er5" size="450" color="white" frame="true" align="right" spinBox="true" caption="3er5, resolution 1.8Å" /> '''THE ACTIVE SITE OF AS...)
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Revision as of 17:34, 20 November 2007
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THE ACTIVE SITE OF ASPARTIC PROTEINASES
Overview
H-189, a synthetic human renin inhibitor, and pepstatin A, a naturally, occurring inhibitor of aspartic proteinases, have been co-crystallized, with the fungal aspartic proteinase endothiapepsin (EC 3.4.23.6). H-189, [Pro-His-Pro-Phe-His-Sta-(statyl)-Val-Ile-His-Lys] is an analogue of human, angiotensinogen. Pepstatin A [Iva(isovaleryl)-Val-Val-Sta-Ala-Sta] is a, blocked pentapeptide which inhibits many aspartic proteinases. The, structures of the complexes have been determined by X-ray diffraction and, refined to crystallographic R-factors of 0.15 and 0.16 at resolutions of, 0.18 nm (1.8 A) and 0.2 nm (2.0 A) respectively. H-189 is in an extended, conformation, in which the statine residue is a dipeptide analogue of P1, and P'1 as indicated by the conformation and network of contacts and, hydrogen bonds. Pepstatin A has an extended conformation to the P'2, alanine residue, but the leucyl side chain of the terminal statine residue, binds back into the S'1 subsite, and an inverse gamma-turn occurs between, P'1 and P'3. The hydroxy moiety of the statine at P1 in both complexes, displaces the solvent molecule that hydrogen-bonds with the catalytic, aspartate residues (32 and 215) in the native enzyme. Solvent molecules, originally present in the native structure at the active site are, displaced on inhibitor binding (12 when pepstatin A binds; 16 when H-189, binds).
About this Structure
3ER5 is a Protein complex structure of sequences from Cryphonectria parasitica. Active as Hydrolase, with EC number 3.4.23.18, 3.4.23.28 and 3.4.23.30 3.4.21.103, 3.4.23.18, 3.4.23.28 and 3.4.23.30 Full crystallographic information is available from OCA.
Reference
X-ray-crystallographic studies of complexes of pepstatin A and a statine-containing human renin inhibitor with endothiapepsin., Bailey D, Cooper JB, Veerapandian B, Blundell TL, Atrash B, Jones DM, Szelke M, Biochem J. 1993 Jan 15;289 ( Pt 2):363-71. PMID:8424781
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