1ee3

Cadmium-substituted bovine pancreatic carboxypeptidase A (alfa-form) at pH 7.5 and 2 mM chloride in monoclinic crystal form

spinqualitylabelsall models 1ee3, resolution 1.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1ee3 is a 1 chain structure with sequence from Bos taurus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.7Å Ligands: CD Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function CBPA1_BOVIN Carboxypeptidase that catalyzes the release of a C-terminal amino acid, but has little or no action with -Asp, -Glu, -Arg, -Lys or -Pro (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Three high-resolution crystal structures of Cd(II)-substituted carboxypeptidase A (CPA) have been determined by X-ray diffraction from crystals prepared in three different buffer systems to assess the effect of pH and ionic strength on the Cd(II) coordination geometry. All crystallize in the space group P2(1) with identical cell dimensions. Cd-CPA(7.5): Cd(II)-substituted CPA prepared at pH 7.5 with [Cl(-)]=2 mM determined to 1.70 A resolution ( R=17.4% and R(free)=19.8%); Cd-CPA(5.5): Cd(II)-substituted CPA prepared at pH 5.5 with [Cl(-)]=2 mM to 2.00 A resolution ( R=16.1% and R(free)=18.6%); Cd-CPA(7.5)-Cl: Cd(II)-substituted CPA prepared at pH 7.5 with [Cl(-)]=250 mM to 1.76 A resolution ( R=16.7% and R(free)=17.8%). No noticeable structural changes were observed between the three structures. Two water molecules coordinate to Cd(II), in contrast to the single water molecule coordinating to Zn(II) in the Zn-CPA structure. No binding sites for anions could be identified, even in the structure with a high concentration of chloride ions. It is suggested that the anion inhibition is due to weak outer-sphere association of Cl(-) ions at several binding sites, shielding the strong positive charge distribution at the surface of the protein near the active site. Based on structural data and a sequence alignment of 18 non-redundant carboxypeptidases, a more elaborate version of the earlier reaction model is proposed that also addresses the transport of water to and from the active site. Conserved residues whose function was not addressed previously delineate the proposed pathways used in the transport of water during catalysis. Three high-resolution crystal structures of cadmium-substituted carboxypeptidase A provide insight into the enzymatic function.,Jensen F, Bukrinsky T, Bjerrum J, Larsen S J Biol Inorg Chem. 2002 Apr;7(4-5):490-9. Epub 2002 Feb 15. PMID:11941507 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Carboxypeptidase 3D structures

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