title: Probing the conformation of bilirubins with monopropionic analogs: a biological, spectroscopic, and molecular modeling study.
abstract: The in vivo metabolism of a bilirubin analog substituted with a propionic acid chain in C8 (5) showed that it is excreted in bile conjugated with glucuronic acid, while a positional isomer substituted with a propionate in C7 (6) is excreted in bile without conjugation. A conformational analysis employing an optimized Monte Carlo method and a mixed Monte Carlo/stochastic dynamics reveals that isomer 5 adopts a 'ridge tile' conformation, stabilized by the presence of three intramolecular hydrogen bonds. On the contrary, isomer 6 exhibits a more closed structure, where impairment in the formation of at least one of the hydrogen bonds occurs. These theoretical predictions agree well with 1H NMR, UV-vis, and TLC data.
authors.affiliation: Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina.
authors.forename: M J
authors.initials: MJ
authors.lastname: Kogan
authors.forename: M E
authors.initials: ME
authors.lastname: Mora
authors.forename: J
authors.initials: J
authors.lastname: Awruch
authors.forename: J M
authors.initials: JM
authors.lastname: Delfino
mesh_terms: D001663:Bilirubin / Q000031:analogs & derivatives* / Q000737:chemistry; D002855:Chromatography, Thin Layer; D005965:Glucuronates; D020723:Glucuronic Acid; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D009010:Monte Carlo Method; D011422:Propionates; D013056:Spectrophotometry, Ultraviolet
chemical_list: D005965:Glucuronates; D011422:Propionates; D020723:Glucuronic Acid; D001663:Bilirubin