RT Journal Article SR Electronic T1 Kinetics and Crystal Structure of Catechol-O-Methyltransferase Complex with Co-Substrate and a Novel Inhibitor with Potential Therapeutic Application JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics SP 795 OP 805 DO 10.1124/mol.62.4.795 VO 62 IS 4 A1 Maria João Bonifácio A1 Margarida Archer A1 Maria L. Rodrigues A1 Pedro M. Matias A1 David A. Learmonth A1 Maria Arménia Carrondo A1 Patrı́cio Soares-da-Silva YR 2002 UL http://molpharm.aspetjournals.org/content/62/4/795.abstract AB 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 asl-3,4-dihydroxyphenylalanine (l-DOPA) viaO-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 theS-adenosyl-l-methionine (SAM) binding site. The 2.0-Å 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.