Complexes of adenosine deaminase with two potent inhibitors: X-ray structures in four independent molecules at pH of maximum activity.Wang, Z., Quiocho, F.A.
(1998) Biochemistry 37: 8314-8324
- PubMed: 9622483
- DOI: 10.1021/bi980324o
- Primary Citation of Related Structures:
- PubMed Abstract:
- 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
- Refined 2.5 A Structure of Murine Adenosine Deaminase at Ph 6.0
Sharff, A.J., Wilson, D.K., Chang, Z., Quiocho, F.A.
(1992) J Mol Biol 226: 917
- 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
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 wi ...
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.
Structural and Computational Biology and Molecular Biophysics Program, Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas 77030, USA.