Modification of a metal ligand in carbonic anhydrase: Crystal structure of His94→Glu human isozyme II

FEBS Letters

Xue, Yafeng¹  Liljas, Anders²  Jonsson, Bengt-Harald¹  Lindskog, Sven¹ 

[1] Department of Biochemistry, Umeå University, S-90187 Umeå, Sweden;Department of Molecular Biophysics, Chemical Center, Lund University, S-22100 Lund, Sweden

关键词: Carbonic anhydrase;    Site-specific mutagenesis;    X-ray crystallography;    Zinc coordination;   

DOI  :  10.1016/0014-5793(94)00936-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

One of the zinc ligands in human carbonic anhydrase II, His⁹⁴, has been replaced with glutamic acid by site-directed mutagenesis. The mutation leads to a less stable zinc binding site and to significant non-local perturbations of the protein structure. The crystals are composed of a mixture of holo- and apoenzyme, and the side chain of Glu⁹⁴ has two conformations. In the holoenzyme, Glu⁹⁴ coordinates to the metal ion and is hydrogen bonded to Gln⁹². In the apo form, Glu⁹⁴ is hydrogen bonded to Asn⁶⁷. The mutation has resulted in a 500-fold decrease of the catalyzed rate of CO₂ hydration (k _cat/K _m).

【 授权许可】

Unknown