1m4l
From Proteopedia
(New page: 200px<br /><applet load="1m4l" size="450" color="white" frame="true" align="right" spinBox="true" caption="1m4l, resolution 1.25Å" /> '''STRUCTURE OF NATIVE ...) |
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| - | [[Image:1m4l.gif|left|200px]]<br /><applet load="1m4l" size=" | + | [[Image:1m4l.gif|left|200px]]<br /><applet load="1m4l" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1m4l, resolution 1.25Å" /> | caption="1m4l, resolution 1.25Å" /> | ||
'''STRUCTURE OF NATIVE CARBOXYPEPTIDASE A AT 1.25 RESOLUTION'''<br /> | '''STRUCTURE OF NATIVE CARBOXYPEPTIDASE A AT 1.25 RESOLUTION'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The crystal structure of the bovine zinc metalloproteinase | + | The crystal structure of the bovine zinc metalloproteinase carboxypeptidase A (CPA) has been refined to 1.25 A resolution based on room-temperature X-ray synchrotron data. The significantly improved structure of CPA at this resolution (anisotropic temperature factors, R factor = 10.4%, R(free) = 14.5%) allowed the modelling of conformational disorders of side chains, improved the description of the protein solvent network (375 water molecules) and provided a more accurate picture of the interactions between the active-site zinc and its ligands. The calculation of standard uncertainties in individual atom positions of the refined model of CPA allowed the deduction of the protonation state of some key residues in the active site and confirmed that Glu72 and Glu270 are negatively charged in the resting state of the enzyme at pH 7.5. These results were further validated by theoretical calculations that showed significant reduction of the pK(a) of these side chains relative to solution values. The distance between the zinc-bound solvent molecule and the metal ion is strongly suggestive of a neutral water molecule and not a hydroxide ion in the resting state of the enzyme. These findings could support both the general acid/general base mechanism, as well as the anhydride mechanism suggested for CPA. |
==About this Structure== | ==About this Structure== | ||
| - | 1M4L is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] with ZN as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [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] Full crystallographic information is available from [http:// | + | 1M4L is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] with <scene name='pdbligand=ZN:'>ZN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [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] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1M4L OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Glick, M.]] | [[Category: Glick, M.]] | ||
[[Category: Goldblum, A.]] | [[Category: Goldblum, A.]] | ||
| - | [[Category: Greenblatt, H | + | [[Category: Greenblatt, H M.]] |
[[Category: Kilshtain-Vardi, A.]] | [[Category: Kilshtain-Vardi, A.]] | ||
[[Category: Shoham, G.]] | [[Category: Shoham, G.]] | ||
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[[Category: metalloproteinase]] | [[Category: metalloproteinase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:51:23 2008'' |
Revision as of 11:51, 21 February 2008
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STRUCTURE OF NATIVE CARBOXYPEPTIDASE A AT 1.25 RESOLUTION
Overview
The crystal structure of the bovine zinc metalloproteinase carboxypeptidase A (CPA) has been refined to 1.25 A resolution based on room-temperature X-ray synchrotron data. The significantly improved structure of CPA at this resolution (anisotropic temperature factors, R factor = 10.4%, R(free) = 14.5%) allowed the modelling of conformational disorders of side chains, improved the description of the protein solvent network (375 water molecules) and provided a more accurate picture of the interactions between the active-site zinc and its ligands. The calculation of standard uncertainties in individual atom positions of the refined model of CPA allowed the deduction of the protonation state of some key residues in the active site and confirmed that Glu72 and Glu270 are negatively charged in the resting state of the enzyme at pH 7.5. These results were further validated by theoretical calculations that showed significant reduction of the pK(a) of these side chains relative to solution values. The distance between the zinc-bound solvent molecule and the metal ion is strongly suggestive of a neutral water molecule and not a hydroxide ion in the resting state of the enzyme. These findings could support both the general acid/general base mechanism, as well as the anhydride mechanism suggested for CPA.
About this Structure
1M4L is a Single protein structure of sequence from Bos taurus with as ligand. Active as Carboxypeptidase A, with EC number 3.4.17.1 Full crystallographic information is available from OCA.
Reference
Refined structure of bovine carboxypeptidase A at 1.25 A resolution., Kilshtain-Vardi A, Glick M, Greenblatt HM, Goldblum A, Shoham G, Acta Crystallogr D Biol Crystallogr. 2003 Feb;59(Pt 2):323-33. Epub 2003, Jan 23. PMID:12554943
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