PT - JOURNAL ARTICLE AU - Maria João Bonifácio AU - Margarida Archer AU - Maria L. Rodrigues AU - Pedro M. Matias AU - David A. Learmonth AU - Maria Arménia Carrondo AU - Patrı́cio Soares-da-Silva TI - Kinetics and Crystal Structure of Catechol-<em>O</em>-Methyltransferase Complex with Co-Substrate and a Novel Inhibitor with Potential Therapeutic Application AID - 10.1124/mol.62.4.795 DP - 2002 Oct 01 TA - Molecular Pharmacology PG - 795--805 VI - 62 IP - 4 4099 - http://molpharm.aspetjournals.org/content/62/4/795.short 4100 - http://molpharm.aspetjournals.org/content/62/4/795.full SO - Mol Pharmacol2002 Oct 01; 62 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.