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Stereoselective Recognition of Monolayers of Cholesterol, ent ‐Cholesterol, and Epicholesterol by an Antibody
Author(s) -
Geva Merav,
Izhaky David,
Mickus Daniel E.,
Rychnovsky Scott D.,
Addadi Lia
Publication year - 2001
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/1439-7633(20010401)2:4<265::aid-cbic265>3.0.co;2-v
Subject(s) - monolayer , chemistry , molecule , stereochemistry , cholesterol , enantiomer , biochemistry , organic chemistry
The interaction between a monoclonal antibody and four distinct monolayers with varying degrees of structural, chemical, and stereochemical similarity were studied and quantified. The antibody, raised and selected against cholesterol monohydrate crystals, interacts with cholesterol monolayers stereospecifically, but not enantiospecifically. Monolayers of ent ‐cholesterol molecules, which are chemically identical to cholesterol and whose structure is the exact mirror image of the cholesterol monolayer, interact with the antibody to the same extent as the cholesterol monolayers. The affinity of the antibody for both enantiomeric monolayers is extremely high. However, the antibody does not interact with monolayers of epicholesterol, which is an epimer of cholesterol: The hydroxy group in epicholesterol is in the 3 α position rather than in the 3 β position, imposing a different angle between the hydroxy group and the rigid steroid backbone, and a different packing of the molecules. Monolayers of triacontanol, a long‐chain primary aliphatic alcohol, interact with the antibody to a lesser extent than the cholesterol and ent ‐cholesterol monolayers, presumably due to the structural flexibility of the triacontanol molecule. The lack of chiral discrimination by the antibody is thus correlated to the level at which the chirality is exposed at the surface of the monolayers.