1FKX

MURINE ADENOSINE DEAMINASE (D296A)

DOI: 10.2210/pdb1FKX/pdb

Classification: AMINOHYDROLASE
Organism(s): Mus musculus
Expression System: Escherichia coli
Mutation(s): Yes

Deposited: 1996-02-29 Released: 1996-08-01
Deposition Author(s): Wilson, D.K., Quiocho, F.A.

Experimental Data Snapshot

Method: X-RAY DIFFRACTION
Resolution: 2.40 Å
R-Value Work: 0.158
R-Value Observed: 0.158

wwPDB Validation 3D Report Full Report

This is version 1.2 of the entry. See complete history.

Literature

Probing the functional role of two conserved active site aspartates in mouse adenosine deaminase.

Sideraki, V., Mohamedali, K.A., Wilson, D.K., Chang, Z., Kellems, R.E., Quiocho, F.A., Rudolph, F.B.

(1996) Biochemistry 35: 7862-7872

PubMed: 8672487 Search on PubMed
DOI: 10.1021/bi952920d
Primary Citation of Related Structures:
1FKX, 1FKW

PubMed Abstract:

Two adjacent aspartates, Asp 295 and Asp 296, playing major roles in the reaction catalyzed by mouse adenosine deaminase (mADA) were altered using site-directed mutagenesis. These mutants were expressed and purified from an ADA-deficient bacterial strain and characterized. Circular dichroism spectroscopy shows the mutants to have unperturbed secondary structure. Their zinc content compares well to that of wild-type enzyme. Changing Asp 295 to a glutamate decreases the kcat but does not alter the Km for adenosine, confirming the importance of this residue in the catalytic process and its minimal role in substrate binding. The crystal structure of the D295E mutant reveals a displacement of the catalytic water from the active site due to the longer glutamate side chain, resulting in the mutant's inability to turn over the substrate. In contrast, Asp 296 mutants exhibit markedly increased Km values, establishing this residue's critical role in substrate binding. The Asp 296->Ala mutation causes a 70-fold increase in the Km for adenosine and retains 0.001% of the wild-type kcat/Km value, whereas the ASP 296->Asn mutant has a 10-fold higher Km and retains 1% of the wild-type kcat/Km value. The structure of the D296A mutant shows that the impaired binding of substrate is caused by the loss of a single hydrogen bond between a carboxylate oxygen and N7 of the purine ring. These results and others discussed below are in agreement with the postulated role of the adjacent aspartates in the catalytic mechanism for mADA.

Related Citations:

A Pre-Transition-State Mimic of an Enzyme: X-Ray Structure of Adenosine Deaminase with Bound 1-Deazaadenosine and Zinc-Activated Water
Wilson, D.K., Quiocho, F.A.
(1993) Biochemistry 32: 1689

Atomic Structure of Adenosine Deaminase Complexed with a Transition-State Analog: Understanding Catalysis and Immunodeficiency Mutations
Wilson, D.K., Rudolph, F.B., Quiocho, F.A.
(1991) Science 252: 1278

Organizational Affiliation:

Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USA.

Macromolecules

Find similar proteins by:

(by identity cutoff) | Structure

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
ADENOSINE DEAMINASE	A	349	Mus musculus	Mutation(s): 1 Gene Names: Ada EC: 3.5.4.4
Find proteins for P03958 (Mus musculus) Explore P03958 Go to UniProtKB: P03958
Protein Feature View Expand
Reference Sequence

Small Molecules

Ligands 2 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram	3D Interactions
PRH Query on PRH Download CCD File	A	6-HYDROXY-1,6-DIHYDRO PURINE NUCLEOSIDE C₁₀ H₁₅ N₄ O₅ WGRXVKRHIMUTPD-YOHZANMFSA-O		Ligand Interaction
ZN Query on ZN Download CCD File	A	ZINC ION Zn PTFCDOFLOPIGGS-UHFFFAOYSA-N		Ligand Interaction