3RLD

Crystal structure of the Y7I mutant of human carbonic anhydrase II

3RLD の概要

• エントリーDOI: 10.2210/pdb3rld/pdb
• 関連するPDBエントリー: 2NXT
• 分子名称: Carbonic anhydrase 2, ZINC ION, SULFATE ION, ... (4 entities in total)
• 機能のキーワード: zinc metalloenzyme, histidine ligands, y7i mutation, 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: 29592.64

構造登録者

Avvaru, B.S.,Mikulski, R.,McKenna, R. (登録日: 2011-04-19, 公開日: 2012-02-08, 最終更新日: 2023-09-13)

主引用文献

Mikulski, R.,Avvaru, B.S.,Tu, C.,Case, N.,McKenna, R.,Silverman, D.N.
Kinetic and crystallographic studies of the role of tyrosine 7 in the active site of human carbonic anhydrase II.
Arch.Biochem.Biophys., 506:181-187, 2011

PubMed Abstract: The rate limiting step in catalysis of bicarbonate dehydration by human carbonic anhydrase II (HCA II) is an intramolecular proton transfer from His64 to the zinc-bound hydroxide. We have examined the role of Tyr7 using site-specific mutagenesis and measuring catalysis by the ¹⁸O exchange method using membrane inlet mass spectrometry. The side chain of Tyr7 in HCA II extends into the active-site cavity about 7 Å from the catalytic zinc atom. Replacement of Tyr7 with eight other amino acids had no effect on the interconversion of bicarbonate and CO₂, but in some cases caused enhancements in the rate constant of proton transfer by nearly 10-fold. The variant Y7I HCA II enhanced intramolecular proton transfer approximately twofold; its structure was determined by X-ray crystallography at 1.5 Å resolution. No changes were observed in the ordered solvent structure in the active-site cavity or in the conformation of the side chain of the proton shuttle His64. However, the first 11 residues of the amino-terminal chain in Y7I HCA II assumed an alternate conformation compared with the wild type. Differential scanning calorimetry showed variants at position 7 had a melting temperature approximately 8 °C lower than that of the wild type.

PubMed: 21145876
DOI: 10.1016/j.abb.2010.12.004

実験手法

X-RAY DIFFRACTION (1.5 Å)