1EE3

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

1EE3 の概要

• エントリーDOI: 10.2210/pdb1ee3/pdb
• 関連するPDBエントリー: 1ELL 1ELM 1cpx
• 分子名称: PROTEIN (CARBOXYPEPTIDASE A), CADMIUM ION (3 entities in total)
• 機能のキーワード: alfa/beta fold, hydrolase
• 由来する生物種: Bos taurus (cattle)
• 細胞内の位置: Secreted, extracellular space: P00730
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 35171.39

構造登録者

Jensen, F.,Bukrinsky, T.,Bjerrum, J.,Larsen, S. (登録日: 2000-01-30, 公開日: 2002-06-26, 最終更新日: 2024-10-09)

主引用文献

Jensen, F.,Bukrinsky, T.,Bjerrum, J.,Larsen, S.
Three high-resolution crystal structures of cadmium-substituted carboxypeptidase A provide insight into the enzymatic function
J.BIOL.INORG.CHEM., 7:490-499, 2002

PubMed Abstract: 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.

PubMed: 11941507
DOI: 10.1007/s00775-001-0324-0

実験手法

X-RAY DIFFRACTION (1.7 Å)