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Adenine Deaminase

  1. Siddhesh S Kamat,
  2. Frank M Raushel

Published Online: 23 SEP 2013

DOI: 10.1002/9781119951438.eibc2172

Encyclopedia of Inorganic and Bioinorganic Chemistry

Encyclopedia of Inorganic and Bioinorganic Chemistry

How to Cite

Kamat, S. S. and Raushel, F. M. 2013. Adenine Deaminase. Encyclopedia of Inorganic and Bioinorganic Chemistry. 1–9.

Author Information

  1. Texas A&M University, College Station, TX, USA

Publication History

  1. Published Online: 23 SEP 2013

Abstract

Adenine deaminase (ADE) is a member of the amidohydrolase superfamily of enzymes and this enzyme catalyzes the deamination of adenine to hypoxanthine. Biologically, this enzyme functions as a member of the purine salvage and catabolism pathways. ADE, expressed and purified from various bacterial sources, exhibits multiple levels of oxygenation modifications that lead to inactivation of catalytic activity. A special iron-free expression protocol is needed to obtain an active form of ADE. The X-ray structure of ADE exhibits a protein-fold that is somewhat different from other members of the amidohydrolase superfamily, although it maintains the central (β/α)8-barrel fold that is a characteristic feature of this superfamily. The active site contains a binuclear metal center with the metal ligands composed of four histidines, an aspartate, a glutamate, and another glutamate that bridges the two metals. The active form of ADE can utilize iron, manganese, or zinc with comparable catalytic efficiencies. Through a series of kinetic, biochemical, spectroscopic, and structural studies, the mechanism of deamination has been elucidated. The di-iron form of ADE shows a unique and aberrant catalase activity. In the presence of hydrogen peroxide the di-iron enzyme catalyzes the formation of reactive oxygen species that modify active site residues thereby resulting in enzyme inactivation.

3D Structure

  • original image

    Ribbon representation of the structure of Atu4426 (PDB code: 3NQB). The structure consists of three domains: N-terminal domain (blue), the central (β/α)8-barrel domain (green), and the C-terminal domain (orange). A long loop (red) connects the N-terminal and C-terminal domains. The manganese ions are represented as magenta spheres. This figure and Figures 2 and 6 were prepared with PyMol.46

Keywords:

  • adenine deaminase;
  • amidohydrolase;
  • binuclear metal center;
  • catalase activity;
  • di-iron catalase