PDBsum entry 1a4m

Hydrolase

PDB id: 1a4m

Contents

Protein chains

349 a.a. *

Ligands

PRH ×4

Metals

_ZN ×4

Waters ×1065

* Residue conservation analysis

PDB id:

1a4m

Name:

Hydrolase

Title:

Ada structure complexed with purine riboside at ph 7.0

Structure:

Adenosine deaminase. Chain: a, b, c, d. Synonym: ada. Engineered: yes

Source:

Mus musculus. House mouse. Organism_taxid: 10090. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.95Å R-factor: 0.193 R-free: 0.281

Authors:

Z.Wang,F.A.Quiocho

Key ref:

Z.Wang and F.A.Quiocho (1998). Complexes of adenosine deaminase with two potent inhibitors: X-ray structures in four independent molecules at pH of maximum activity. Biochemistry, 37, 8314-8324. PubMed id: 9622483 DOI: 10.1021/bi980324o

Date:

31-Jan-98 Release date: 14-Oct-98

Protein chains

P03958  (ADA_MOUSE) -  Adenosine deaminase from Mus musculus

Seq: 352 a.a.

Struc: 349 a.a.

Enzyme reactions

• Enzyme class: E.C.3.5.4.4 - adenosine deaminase.
• Reaction:
  1. adenosine + H2O + H⁺ = inosine + NH4⁺
  2. 2'-deoxyadenosine + H2O + H⁺ = 2'-deoxyinosine + NH4⁺

adenosine + H2O + H(+) = inosine (Bound ligand (Het Group name = PRH) corresponds exactly) + NH4(+)

2'-deoxyadenosine (Bound ligand (Het Group name = PRH) matches with 85.00% similarity) + H2O + H(+) = 2'-deoxyinosine + NH4(+)

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

reference

DOI no: 10.1021/bi980324o

Biochemistry 37:8314-8324 (1998)

PubMed id: 9622483

Complexes of adenosine deaminase with two potent inhibitors: X-ray structures in four independent molecules at pH of maximum activity.

Z.Wang, F.A.Quiocho.

ABSTRACT

Adenosine deaminase, which catalyzes the irreversible hydrolytic deamination of adenosine nucleosides to inosine nucleosides and ammonia, is a key enzyme in purine metabolism and lymphoid development. The X-ray structures of murine adenosine deaminase with bound potent inhibitors (Ki values approximately 10(-13) M) (8R)-hydroxyl-2'-deoxycoformycin (pentostatin), a transition state analogue, and (6S)-hydroxyl-1,6-dihydropurine riboside, a reaction coordinate analogue, have been determined and refined to resolutions of 2.6 and 1.95 A, respectively. Crystals of both complexes were obtained at pH 7, where the enzyme is fully active, in an identical space group with the asymmetric unit containing four molecules. In addition to the very high degree of similarity between the four independent molecules in each complex structure, there is also considerable structural similarity of the complex with the dihydropurine riboside with that of an identical complex previously determined at pH 4.2 where the enzyme is 20% active. The interactions between the enzyme and the two analogues are extremely similar. These include the coordination of the 8R- or 6S-hydroxyl group of the analogues to the Zn2+ which mainly contributes to the strong potency and very high degree of stereospecificity of inhibition by these analogues. The interactions are further indicative of the structural and chemical requirements of substrates. These structures and recent site-directed mutagenesis have further shed light on the catalytic mechanism of the enzyme.