On how the conformation of biliverdins influences their reduction to bilirubins: a biological and molecular modeling study.
The cyclic 2,18-bridged biliverdin (2) is excreted in rat bile without reduction to the corresponding bilirubin. Conformational analysis, employing an optimized Monte Carlo method and a mixed Monte Carlo/stochastic dynamics, reveals that biliverdin IXalpha (1) and the cyclic analogue 2 adopt 'lock washer' conformations, stabilized by the presence of intramolecular hydrogen bonds between N23...H22N and, to a lesser extent, between N23...H24N. Although 2 is very similar in overall shape to 1, the former adopts a 'locked lock washer' conformation unable to undergo fluctuations, thus possibly hampering a proper recognition by biliverdin reductase.
Mora
María E
ME
Departamento de Química Orgánica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, 1113 Buenos Aires, Argentina.
Bari
Sara E
SE
Awruch
Josefina
J
Delfino
José M
JM
D000818:Animals; D001663:Bilirubin / Q000737:chemistry* / Q000378:metabolism / Q000652:urine; D001664:Biliverdine / Q000737:chemistry* / Q000378:metabolism / Q000652:urine; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011487:Protein Conformation; D051381:Rats; D013269:Stochastic Processes
D001664:Biliverdine; D001663:Bilirubin