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. 1988 Aug;85(16):5759–5763. doi: 10.1073/pnas.85.16.5759

Conformational analysis of 9β,19-cyclopropyl sterols: Detection of the pseudoplanar conformer by nuclear Overhauser effects and its functional implications

W David Nes *, Mabry Benson †, Robert E Lundin †, Phu H Le *
PMCID: PMC281844  PMID: 16593969

Abstract

Nuclear Overhauser difference spectroscopy and variable temperature studies of the 9β,19-cyclopropyl sterols 24,25-dehydropollinastanol (4,4-desmethyl-5α-cycloart-24-en-3β-ol) and cyclolaudenol [(24S)-24-methyl-5α-cycloart-25(27)-en-3β-ol] have shown the solution conformation of the B/C rings to be twist-chair/twist-boat rather than boat/chair as suggested in the literature. This is very similar to the known crystal structure conformation of 9β,19-cyclopropyl sterols. The effect of these conformations on the molecular shape is highly significant: the first conformation orients into a pseudoplanar or flat shape analogous to lanosterol, whereas the latter conformation exhibits a bent shape. The results are interpreted to imply that, for conformational reasons, cyclopropyl sterols can be expected to maintain the pseudoplanar shape in membrane bilayers.

Keywords: periplanar structure; cycloartenol; 24,25-dehydropollinastanol; membranes; sterols

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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