TY - JOUR T1 - Solution Conformations of Ethyl-1'-Methylbutylbarbituric Acids: Implications for Drug-Receptor Site Interactions JF - Molecular Pharmacology JO - Mol Pharmacol SP - 470 LP - 477 VL - 11 IS - 4 AU - G. DOYLE DAVES, JR. AU - RODNEY B. BELSHEE AU - WILLIAM R. ANDERSON, JR. AU - HALL DOWNES Y1 - 1975/07/01 UR - http://molpharm.aspetjournals.org/content/11/4/470.abstract N2 - Solution conformations of 5-ethyl-5-(1'-methylbutyl)-, 5-ethyl-5-(1',3'-dimethylbutyl)-, and 5-ethyl-5-(1',3',3'-trimethylbutyl)barbituric acids in a variety of solvents have been studied by nuclear magnetic resonance techniques. Implications of the results obtained in this study for discrimination between the enantiomers of 5-ethyl-5-(1',3'-dimethylbutyl)barbituric acid [R-(+), excitatory, and S-(-), depressant] at the excitatory receptor site are discussed. It is suggested that discrimination between the enantiomers is based primarily on a required binding orientation of the pyrimidinetrione ring and differing aliphatic side chain geometries resulting from a strong conformational preference of the isopropyl termini. ER -