title: Kinetics and crystal structure of catechol-o-methyltransferase complex with co-substrate and a novel inhibitor with potential therapeutic application.
abstract: Catechol-O-methyltransferase (COMT; E.C. 2.1.1.6) is a ubiquitous enzyme in nature that plays an important role in the metabolism of catechol neurotransmitters and xenobiotics. In particular, inactivation of drugs such as L-3,4-dihydroxyphenylalanine (L-DOPA) via O-methylation is of relevant pharmacological importance, because L-DOPA is currently the most effective drug used in the treatment of Parkinson's disease. This justified the interest in developing COMT inhibitors as potential adjuncts to L-DOPA therapy. The kinetics of inhibition by BIA 3-335 (1-[3,4-dihydroxy-5-nitrophenyl]-3-(N-3'-trifluormethylphenyl)-piperazine-1-propanone dihydrochloride) were characterized using recombinant rat soluble COMT. BIA 3-335 was found to act as a potent, reversible, tight-binding inhibitor of COMT with a K(i) of 6.0 +/- 1.6 nM and displaying a competitive inhibition toward the substrate binding site and uncompetitive inhibition toward the S-adenosyl-L-methionine (SAM) binding site. The 2.0-A resolution crystal structure of COMT in complex with its cosubstrate SAM and a novel inhibitor BIA 3-335 shows the atomic interactions between the important residues at the active site and the inhibitor. This is the first report of a three-dimensional structure determination of COMT complexed with a potent, reversible, and tight-binding inhibitor that is expected to have therapeutic applications.
authors.affiliation: Department of Research and Development, BIAL, S. Mamede do Coronado, Portugal.
authors.forename: Maria João
authors.initials: MJ
authors.lastname: Bonifácio
authors.forename: Margarida
authors.initials: M
authors.lastname: Archer
authors.forename: Maria L
authors.initials: ML
authors.lastname: Rodrigues
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Matias
authors.forename: David A
authors.initials: DA
authors.lastname: Learmonth
authors.forename: Maria Arménia
authors.initials: MA
authors.lastname: Carrondo
authors.forename: Patrício
authors.initials: P
authors.lastname: Soares-Da-Silva
mesh_terms: D000818:Animals; D001665:Binding Sites; D002394:Catechol O-Methyltransferase / Q000737:chemistry*; D065098:Catechol O-Methyltransferase Inhibitors; D003460:Crystallization; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology; D007700:Kinetics; D051379:Mice; D008958:Models, Molecular; D008968:Molecular Conformation; D010879:Piperazines / Q000737:chemistry* / Q000494:pharmacology; D013379:Substrate Specificity
chemical_list: C466310:BIA 3-335; D065098:Catechol O-Methyltransferase Inhibitors; D004791:Enzyme Inhibitors; D010879:Piperazines; D002394:Catechol O-Methyltransferase