1pca
From Proteopedia
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| - | [[Image:1pca.gif|left|200px]] | + | [[Image:1pca.gif|left|200px]] |
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| - | '''THREE DIMENSIONAL STRUCTURE OF PORCINE PANCREATIC PROCARBOXYPEPTIDASE A. A COMPARISON OF THE A AND B ZYMOGENS AND THEIR DETERMINANTS FOR INHIBITION AND ACTIVATION''' | + | {{Structure |
| + | |PDB= 1pca |SIZE=350|CAPTION= <scene name='initialview01'>1pca</scene>, resolution 2.0Å | ||
| + | |SITE= | ||
| + | |LIGAND= <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene>, <scene name='pdbligand=CIT:CITRIC+ACID'>CIT</scene> and <scene name='pdbligand=VAL:VALINE'>VAL</scene> | ||
| + | |ACTIVITY= [http://en.wikipedia.org/wiki/Carboxypeptidase_A Carboxypeptidase A], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.17.1 3.4.17.1] | ||
| + | |GENE= | ||
| + | }} | ||
| + | |||
| + | '''THREE DIMENSIONAL STRUCTURE OF PORCINE PANCREATIC PROCARBOXYPEPTIDASE A. A COMPARISON OF THE A AND B ZYMOGENS AND THEIR DETERMINANTS FOR INHIBITION AND ACTIVATION''' | ||
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==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1PCA is a [ | + | 1PCA is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Sus_scrofa Sus scrofa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1PCA OCA]. |
==Reference== | ==Reference== | ||
| - | Three-dimensional structure of porcine pancreatic procarboxypeptidase A. A comparison of the A and B zymogens and their determinants for inhibition and activation., Guasch A, Coll M, Aviles FX, Huber R, J Mol Biol. 1992 Mar 5;224(1):141-57. PMID:[http:// | + | Three-dimensional structure of porcine pancreatic procarboxypeptidase A. A comparison of the A and B zymogens and their determinants for inhibition and activation., Guasch A, Coll M, Aviles FX, Huber R, J Mol Biol. 1992 Mar 5;224(1):141-57. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/1548696 1548696] |
[[Category: Carboxypeptidase A]] | [[Category: Carboxypeptidase A]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
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[[Category: hydrolase(c-terminal peptidase)]] | [[Category: hydrolase(c-terminal peptidase)]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 13:22:36 2008'' |
Revision as of 11:22, 20 March 2008
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| , resolution 2.0Å | |||||||
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| Ligands: | , and | ||||||
| Activity: | Carboxypeptidase A, with EC number 3.4.17.1 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
THREE DIMENSIONAL STRUCTURE OF PORCINE PANCREATIC PROCARBOXYPEPTIDASE A. A COMPARISON OF THE A AND B ZYMOGENS AND THEIR DETERMINANTS FOR INHIBITION AND ACTIVATION
Overview
The three-dimensional structure of procarboxypeptidase A (PCPA) from porcine pancreas has been determined at 2 A resolution and refined to a crystallographic R-factor of 0.198, with a root-mean-square deviation from ideal values for bond lengths of 0.015 A and for angles of 2.1 degrees. It is compared with procarboxypeptidase B (PCPB) from the same tissue. The 94/95 residue activation segments of PCPA/PCPB have equivalent folds: an N-terminal globular region with an open sandwich antiparallel alpha/antiparallel beta topology, followed by an extended alpha-helical segment, the connection to the enzyme. Alignment of the secondary structures of the activation segments of PCPA and PCPB (residues A1 to A99) indicates a two residue insertion between residues A34 and A35 and a C-terminal helix that is two turns longer in PCPA compared to PCPB. A deletion is observed between residues A43 to A45, the region containing the short 3(10) helix that covers the active site in PCPB. The globular region (A4 to A80) shields the preformed active center of carboxypeptidase A (CPA), but none of the residues involved in catalysis makes direct contacts with the activation segment. In contrast, subsites S2, S3 and S4 of the enzyme, involved in the binding of peptidic substrates, are blocked by specific contacts with residues AspA36, TrpA38, ArgA47, AspA53 and GluA86 of the activation segment. It has been described that several residues of CPA exhibit different conformations in the free enzyme compared to when substrate is bound: Arg127, Arg145, Glu270 and Tyr248. In PCPA all of these residues are found in the "active" conformation, as if substrate were actually bound. The presence of a ligand, tentatively interpreted as a free amino acid (Val) in the active center could explain this fact. The connecting region (A80 to A99), the target for proteolytic activation, establishes fewer contacts with the enzyme in PCPA than in PCPB. The activation segment of PCPA (A4 to A99) remains bound to the enzyme after the first trypsin cleavage between ArgA99-Ala1 probably due to the stability conferred on it by the alpha-helix (alpha 3) of the connecting segment. These and other structural features may explain the differences in intrinsic activity and different rates or proteolytic activation of each zymogen.
About this Structure
1PCA is a Single protein structure of sequence from Sus scrofa. Full crystallographic information is available from OCA.
Reference
Three-dimensional structure of porcine pancreatic procarboxypeptidase A. A comparison of the A and B zymogens and their determinants for inhibition and activation., Guasch A, Coll M, Aviles FX, Huber R, J Mol Biol. 1992 Mar 5;224(1):141-57. PMID:1548696
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