PDBsum entry 1cve

Lyase(oxo-acid)

PDB id: 1cve

Contents

Protein chain

255 a.a. *

Metals

_ZN

Waters ×129

* Residue conservation analysis

PDB id:

1cve

Name:

Lyase(oxo-acid)

Title:

Structural consequences of redesigning a protein-zinc binding site

Structure:

Carbonic anhydrase ii. Chain: a. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606

Resolution:

2.25Å R-factor: 0.182

Authors:

J.A.Ippolito,D.W.Christianson

Key ref:

J.A.Ippolito and D.W.Christianson (1994). Structural consequences of redesigning a protein-zinc binding site. Biochemistry, 33, 15241-15249. PubMed id: 7803386 DOI: 10.1021/bi00255a004

Date:

21-Jun-94 Release date: 30-Nov-94

Protein chain

P00918  (CAH2_HUMAN) -  Carbonic anhydrase 2 from Homo sapiens

Seq: 260 a.a.

Struc: 255 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class 2: E.C.4.2.1.1 - carbonic anhydrase.
• Reaction: hydrogencarbonate + H⁺ = CO2 + H2O
• Cofactor: Zn(2+)
• Enzyme class 3: E.C.4.2.1.69 - cyanamide hydratase.
• Reaction: urea = cyanamide + H2O

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1021/bi00255a004

Biochemistry 33:15241-15249 (1994)

PubMed id: 7803386

Structural consequences of redesigning a protein-zinc binding site.

J.A.Ippolito, D.W.Christianson.

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)