3KOI

Crystal structure of cobalt (III) human carbonic anhydrase II at pH 6.0

3KOI の概要

• エントリーDOI: 10.2210/pdb3koi/pdb
• 関連するPDBエントリー: 3KOK 3KON 3KS3
• 分子名称: Carbonic anhydrase 2, COBALT (III) ION (3 entities in total)
• 機能のキーワード: carbonic anhydrase, metalloenzyme, cobalt substitution, crystal ph, lyase
• 由来する生物種: Homo sapiens (human)
• 細胞内の位置: Cytoplasm: P00918
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 29348.00

構造登録者

Avvaru, B.S. (登録日: 2009-11-13, 公開日: 2010-08-25, 最終更新日: 2024-02-21)

主引用文献

Avvaru, B.S.,Arenas, D.J.,Tu, C.,Tanner, D.B.,McKenna, R.,Silverman, D.N.
Comparison of solution and crystal properties of Co(II)-substituted human carbonic anhydrase II.
Arch.Biochem.Biophys., 502:53-59, 2010

PubMed Abstract: The visible absorption of crystals of Co(II)-substituted human carbonic anhydrase II (Co(II)-HCA II) were measured over a pH range of 6.0-11.0 giving an estimate of pK(a) 8.4 for the ionization of the metal-bound water in the crystal. This is higher by about 1.2 pK(a) units than the pK(a) near 7.2 for Co(II)-CA II in solution. This effect is attributed to a nonspecific ionic strength effect of 1.4M citrate in the precipitant solution used in the crystal growth. A pK(a) of 8.3 for the aqueous ligand of the cobalt was measured for Co(II)-HCA II in solution containing 0.8M citrate. Citrate is not an inhibitor of the catalytic activity of Co(II)-HCA II and was not observed in crystal structures. The X-ray structures at 1.5-1.6A resolution of Co(II)-HCA II were determined for crystals prepared at pH 6.0, 8.5 and 11.0 and revealed no conformational changes of amino-acid side chains as a result of the use of citrate. However, the studies of Co(II)-HCA II did reveal a change in metal coordination from tetrahedral at pH 11 to a coordination consistent with a mixed population of both tetrahedral and penta-coordinate at pH 8.5 to an octahedral geometry characteristic of the oxidized enzyme Co(III)-HCA II at pH 6.0.

PubMed: 20637176
DOI: 10.1016/j.abb.2010.07.010

実験手法

X-RAY DIFFRACTION (1.64 Å)