 |
PDBsum entry 1cve
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Lyase(oxo-acid)
|
PDB id
|
|
|
|
1cve
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
References listed in PDB file
|
|
|
Key reference
|
|
|
Title
|
|
Structural consequences of redesigning a protein-Zinc binding site.
|
|
|
Authors
|
|
J.A.Ippolito,
D.W.Christianson.
|
|
|
Ref.
|
|
Biochemistry, 1994,
33,
15241-15249.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
Note In the PDB file this reference is
annotated as "TO BE PUBLISHED".
The citation details given above were identified by an automated
search of PubMed on title and author
names, giving a
perfect match.
|
|
|
|
Abstract
|
|
|
In order to probe the structural importance of zinc ligands in the active site
of human carbonic anhydrase II (CAII), we have determined the three-dimensional
structures of H94C (in metal-bound form), H94C-BME (i.e., disulfide-linked with
beta-mercaptoethanol), H94A, H96C, H119C, and H119D variants of CAII by X-ray
crystallographic methods at resolutions of 2.2, 2.35, 2.25, 2.3, 2.2, and 2.25
A, respectively. Each variant crystallizes isomorphously with the wild-type
enzyme, in which zinc is tetrahedrally coordinated by H94, H96, H119, and
hydroxide ion. The structure of H94C CAII reveals the successful substitution of
the naturally occurring histidine zinc ligand by a cysteine thiolate, and metal
coordination by C94 is facilitated by the plastic structural response of the
beta-sheet superstructure. Importantly, the resulting structure represents the
catalytically active form of the enzyme reported previously [Alexander, R. S.,
Kiefer, L. L., Fierke, C. A., & Christianson, D. W. (1993) Biochemistry 32,
1510-1518]. Contrastingly, the structure of H96C CAII reveals that the
engineered side chain does not coordinate to zinc; instead, zinc is
tetrahedrally liganded by H94, H119, and two solvent molecules. Thus, the
beta-sheet superstructure is not sufficiently plastic in this location to allow
C96 to coordinate to the metal ion. Substitution of the thiolate or carboxylate
group for wild-type histidine in H119C and H119D CAIIs reveals that tetrahedral
metal coordination is maintained in each variant; however, since there is no
plastic structural response of the corresponding beta-strand, a longer
metal-ligand separation results.(ABSTRACT TRUNCATED AT 250 WORDS)
|
|
|
|
|
|
|
