Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5417110 | Journal of Molecular Structure: THEOCHEM | 2009 | 6 Pages |
Abstract
Ab initio methods were utilized in a gas-phase systematic conformational search of bilirubin conformers. The whole molecule was divided into four fragments. Most stable conformers of them were employed to build 196 conformers of the complete bilirubin molecule. Initial geometries were optimized using HF/3-21G level of theory and the minimum energy conformers were then reoptimized at B3LYP/6-31G(d) level. Ridge-tile conformer was the most stable one, in perfect agreement with X-ray data. We found that while tetrapyrrole backbone shows some flexibility, propionic acid side chains have a greater influence in bilirubin conformation because they can interact through different hydrogen bond patterns with the backbone and between them.
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Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
Esteban Gabriel Vega Hissi, Juan Ceferino Garro MartÃnez, Graciela Nilda Zamarbide, Mario Rinaldo Estrada, Svend J. Knak Jensen, Francisco Tomás-Vert, Imre G. Csizmadia,