3cpa
From Proteopedia
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[[Image:3cpa.jpg|left|200px]] | [[Image:3cpa.jpg|left|200px]] | ||
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'''X-RAY CRYSTALLOGRAPHIC INVESTIGATION OF SUBSTRATE BINDING TO CARBOXYPEPTIDASE A AT SUBZERO TEMPERATURE''' | '''X-RAY CRYSTALLOGRAPHIC INVESTIGATION OF SUBSTRATE BINDING TO CARBOXYPEPTIDASE A AT SUBZERO TEMPERATURE''' | ||
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==About this Structure== | ==About this Structure== | ||
| - | 3CPA is a [[Single protein]] structure | + | 3CPA is a [[Single protein]] structure. This structure supersedes the now removed PDB entry [http://oca.weizmann.ac.il/oca-bin/send-pdb?obs=1&id=1cpa 1cpa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3CPA OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Lipscomb, W N.]] | [[Category: Lipscomb, W N.]] | ||
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Revision as of 10:58, 30 April 2008
X-RAY CRYSTALLOGRAPHIC INVESTIGATION OF SUBSTRATE BINDING TO CARBOXYPEPTIDASE A AT SUBZERO TEMPERATURE
Overview
A high-resolution x-ray crystallographic investigation of the complex between carboxypeptidase A (CPA; peptidyl-L-amino-acid hydrolase, EC 3.4.17.1) and the slowly hydrolyzed substrate glycyl-L-tyrosine was done at -9 degrees C. Although this enzyme-substrate complex has been the subject of earlier crystallographic investigation, a higher resolution electron-density map of the complex with greater occupancy of the substrate was desired. All crystal chemistry (i.e., crystal soaking and x-ray data collection) was performed on a diffractometer-mounted flow cell, in which the crystal was immobilized. The x-ray data to 1.6-A resolution have yielded a well-resolved structure in which the zinc ion of the active site is five-coordinate: three enzyme residues (glutamate-72, histidine-69, and histidine-196) and the carbonyl oxygen and amino terminus of glycyl-L-tyrosine complete the coordination polyhedron of the metal. These results confirm that this substrate may be bound in a nonproductive manner, because the hydrolytically important zinc-bound water has been displaced and excluded from the active site. It is likely that all dipeptide substrates of carboxypeptidase A that carry an unprotected amino terminus are poor substrates because of such favorable bidentate coordination to the metal ion of the active site.
About this Structure
3CPA is a Single protein structure. This structure supersedes the now removed PDB entry 1cpa. Full crystallographic information is available from OCA.
Reference
X-ray crystallographic investigation of substrate binding to carboxypeptidase A at subzero temperature., Christianson DW, Lipscomb WN, Proc Natl Acad Sci U S A. 1986 Oct;83(20):7568-72. PMID:3463986 Page seeded by OCA on Wed Apr 30 13:58:25 2008
