title: 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.
abstract: (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.
authors.affiliation: Division of Structural Biology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland.
authors.forename: Paola
authors.initials: P
authors.lastname: Storici
authors.forename: Jian
authors.initials: J
authors.lastname: Qiu
authors.forename: Tilman
authors.initials: T
authors.lastname: Schirmer
authors.forename: Richard B
authors.initials: RB
authors.lastname: Silverman
mesh_terms: 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
chemical_list: 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