Mechanistic crystallography. Mechanism of inactivation of gamma-aminobutyric acid aminotransferase by (1R,3S,4S)-3-amino-4-fluorocyclopentane-1-carboxylic acid as elucidated by crystallography.
(1R,3S,4S)-3-Amino-4-fluorocyclopentane-1-carboxylic acid (7) was previously shown to be a mechanism-based inactivator of gamma-aminobutyric acid aminotransferase (GABA-AT) [Qiu, J. and Silverman, R. B. (2000) J. Med. Chem. 43, 706-720]. Two mechanisms were considered as reasonable possibilities, a Michael addition mechanism and an enamine mechanism. On the basis of a variety of chemical studies, including tedious radiolabeling experiments, it was concluded that inactivation by 7 proceeds by a Michael addition mechanism. Here, a crystal structure of 7 bound to pig liver GABA-AT is reported, which clearly demonstrates that the adduct formed is derived from an enamine mechanism. This represents another example of how crystallography is an important tool for elucidation of inactivation mechanisms.
Storici
Paola
P
Division of Structural Biology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland.
Qiu
Jian
J
Schirmer
Tilman
T
Silverman
Richard B
RB
D000612:4-Aminobutyrate Transaminase / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000378:metabolism; D000588:Amines / Q000737:chemistry; D000596:Amino Acids / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002264:Carboxylic Acids / Q000737:chemistry* / Q000378:metabolism; D003460:Crystallization; D018360:Crystallography, X-Ray / Q000379:methods; D003517:Cyclopentanes; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000378:metabolism; D008024:Ligands; D008099:Liver / Q000201:enzymology; D008956:Models, Chemical; D008958:Models, Molecular; D011487:Protein Conformation; D011732:Pyridoxal Phosphate / Q000737:chemistry; D013379:Substrate Specificity; D013552:Swine
C480544:3-amino-4-(difluoromethylidene)cyclopentanecarboxylic acid; D000588:Amines; D000596:Amino Acids; D002264:Carboxylic Acids; D003517:Cyclopentanes; D004791:Enzyme Inhibitors; D008024:Ligands; D011732:Pyridoxal Phosphate; D000612:4-Aminobutyrate Transaminase