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Modification of a metal ligand in carbonic anhydrase: Crystal structure of His 94 →Glu human isozyme II
Author(s) -
Xue Yafeng,
Jonsson Bengt-Harald,
Liljas Anders,
Lindskog Sven
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)00936-8
Subject(s) - carbonic anhydrase , chemistry , zinc , crystal structure , carbonic anhydrase ii , metal , glutamic acid , enzyme , crystallography , histidine , ligand (biochemistry) , site directed mutagenesis , active site , mutagenesis , stereochemistry , mutation , amino acid , biochemistry , organic chemistry , receptor , mutant , gene
One of the zinc ligands in human carbonic anhydrase II, His 94 , 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 Glu 94 has two conformations. In the holoenzyme, Glu 94 coordinates to the metal ion and is hydrogen bonded to Gln 92 . In the apo form, Glu 94 is hydrogen bonded to Asn 67 . The mutation has resulted in a 500‐fold decrease of the catalyzed rate of CO 2 hydration ( k cat / K m ).