1eai
From Proteopedia
(New page: 200px<br /><applet load="1eai" size="450" color="white" frame="true" align="right" spinBox="true" caption="1eai, resolution 2.4Å" /> '''COMPLEX OF ASCARIS CH...) |
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| - | [[Image:1eai.jpg|left|200px]]<br /><applet load="1eai" size=" | + | [[Image:1eai.jpg|left|200px]]<br /><applet load="1eai" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1eai, resolution 2.4Å" /> | caption="1eai, resolution 2.4Å" /> | ||
'''COMPLEX OF ASCARIS CHYMOTRPSIN/ELASTASE INHIBITOR WITH PORCINE ELASTASE'''<br /> | '''COMPLEX OF ASCARIS CHYMOTRPSIN/ELASTASE INHIBITOR WITH PORCINE ELASTASE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: The intestinal parasitic worm, Ascaris suum, produces a | + | BACKGROUND: The intestinal parasitic worm, Ascaris suum, produces a variety of protein inhibitors that defend the organism against the host's proteinases. Eight different proteins from Ascaris suum have been identified as inhibitors of serine proteinases, targeting chymotrypsin, elastase and trypsin. These inhibitors share 30-40% sequence identity with one another, but have virtually no sequence identity with members of any of the other families of serine proteinase inhibitors. RESULTS: The crystal structure of the complex of porcine pancreatic elastase with a chymotrypsin/elastase inhibitor from Ascaris suum (the C/E-1 inhibitor) has been solved to 2.4 A resolution by the molecular replacement method. The C/E-1 inhibitor exhibits a novel folding motif. There are only two small beta-sheets and two single-turn 3(10)-helices in this inhibitor. Unlike the majority of proteins, the C/E-1 inhibitor does not have a hydrophobic core. The presence and unique topography of the five disulfide bridges suggests that they play important roles in maintaining the tertiary structure of the inhibitor. In addition, the side chains of several charged residues from electrostatic and hydrogen-bonding cascades, which also probably compensate for the lack of extensive secondary structures and a hydrophobic core. The reactive-site loop of this inhibitor displays a conformation that is characteristic of most serine proteinase inhibitors. CONCLUSIONS: The structure of the C/E-1 inhibitor confirms that inhibitors from Ascaris suum belong to a novel family of proteinase inhibitors. It also provides conclusive evidence for the correct disulfide bridge connections. The C/E-1 inhibitor probably acts by a common inhibitory mechanism proposed for other substrate-like protein inhibitors of serine proteinases. The unusual molecular scaffolding presents a challenge to current folding algorithms. Proteins like the C/E-1 inhibitor may provide a valuable model system to study how the primary sequence of a protein dictates its three-dimensional structure. |
==About this Structure== | ==About this Structure== | ||
| - | 1EAI 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]. Active as [http://en.wikipedia.org/wiki/Pancreatic_elastase Pancreatic elastase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.21.36 3.4.21.36] Full crystallographic information is available from [http:// | + | 1EAI 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]. Active as [http://en.wikipedia.org/wiki/Pancreatic_elastase Pancreatic elastase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.21.36 3.4.21.36] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1EAI OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Protein complex]] | [[Category: Protein complex]] | ||
[[Category: Sus scrofa]] | [[Category: Sus scrofa]] | ||
| - | [[Category: Bernard, V | + | [[Category: Bernard, V D.]] |
[[Category: Huang, K.]] | [[Category: Huang, K.]] | ||
| - | [[Category: James, M | + | [[Category: James, M N.G.]] |
| - | [[Category: Peanasky, R | + | [[Category: Peanasky, R J.]] |
| - | [[Category: Strynadka, N | + | [[Category: Strynadka, N C.J.]] |
[[Category: ascaris summ]] | [[Category: ascaris summ]] | ||
[[Category: elastase]] | [[Category: elastase]] | ||
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[[Category: serine proteinase]] | [[Category: serine proteinase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:25:40 2008'' |
Revision as of 10:25, 21 February 2008
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COMPLEX OF ASCARIS CHYMOTRPSIN/ELASTASE INHIBITOR WITH PORCINE ELASTASE
Overview
BACKGROUND: The intestinal parasitic worm, Ascaris suum, produces a variety of protein inhibitors that defend the organism against the host's proteinases. Eight different proteins from Ascaris suum have been identified as inhibitors of serine proteinases, targeting chymotrypsin, elastase and trypsin. These inhibitors share 30-40% sequence identity with one another, but have virtually no sequence identity with members of any of the other families of serine proteinase inhibitors. RESULTS: The crystal structure of the complex of porcine pancreatic elastase with a chymotrypsin/elastase inhibitor from Ascaris suum (the C/E-1 inhibitor) has been solved to 2.4 A resolution by the molecular replacement method. The C/E-1 inhibitor exhibits a novel folding motif. There are only two small beta-sheets and two single-turn 3(10)-helices in this inhibitor. Unlike the majority of proteins, the C/E-1 inhibitor does not have a hydrophobic core. The presence and unique topography of the five disulfide bridges suggests that they play important roles in maintaining the tertiary structure of the inhibitor. In addition, the side chains of several charged residues from electrostatic and hydrogen-bonding cascades, which also probably compensate for the lack of extensive secondary structures and a hydrophobic core. The reactive-site loop of this inhibitor displays a conformation that is characteristic of most serine proteinase inhibitors. CONCLUSIONS: The structure of the C/E-1 inhibitor confirms that inhibitors from Ascaris suum belong to a novel family of proteinase inhibitors. It also provides conclusive evidence for the correct disulfide bridge connections. The C/E-1 inhibitor probably acts by a common inhibitory mechanism proposed for other substrate-like protein inhibitors of serine proteinases. The unusual molecular scaffolding presents a challenge to current folding algorithms. Proteins like the C/E-1 inhibitor may provide a valuable model system to study how the primary sequence of a protein dictates its three-dimensional structure.
About this Structure
1EAI is a Protein complex structure of sequences from Ascaris suum and Sus scrofa. Active as Pancreatic elastase, with EC number 3.4.21.36 Full crystallographic information is available from OCA.
Reference
The molecular structure of the complex of Ascaris chymotrypsin/elastase inhibitor with porcine elastase., Huang K, Strynadka NC, Bernard VD, Peanasky RJ, James MN, Structure. 1994 Jul 15;2(7):679-89. PMID:7922044
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