ISSN:
1434-4475
Keywords:
Bilirubin
;
Conformational analysis
;
Force field calculations
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The energy hypersurface of rubinoid bile pigments is calculated using a force field model previously described. Two cases are observed. I: The pigment is substituted symmetrically or unsymmetrically by apolar groups. This results in a very shallow energy valley containing several enantiomeric conformers of approximately equal energies. II: Substitution by polar groups, especially in position 8 and 12 of the rubin skeleton, (e.g.−CH2−CH2−COOH) is followed by a “lock in” bonding between such groups and the lactam ring functions. Thereby only two enantiomeric conformers, which are energetically stabilized, are possible. The barrier between these species amounts to about 40 kJ/mol. These results are compared with the experimental facts available so far. An analysis of the corresponding energy hypersurfaces of the diastereomeric forms of (Z,Z)-, (E,Z)-, (Z,E)- and (E,E)-configurations is given as well.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00904684
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