Structure and nomenclature
Ceramides may be found in free form or included in more complex lipids such as
sphingomyelin or various glycosphingolipids. Analysis of the ceramide moieties of these
complex lipids makes it possible to determine their individual molecular species since
Ceramides are combinations of both a fatty acid and a long-chain base.
Free ceramides which are most frequently present in trace amounts in biological extracts
must be derivatized directly before separation and HPLC analysis. When ceramides are
prepared from phospholipids or glycosphingolipids (in the range 0.1-10 mg), they are more
conveniently purified by column chromatography before further analysis.
The lipidologist may want to quantify or to know the structure of ceramides. In all cases,
their purification from the whole bulk of lipids is necessary, either before or after
derivatization, to allow their quantification. This quantification may be carried out by
the estimation of ceramide components (fatty acids, bases) or directly by the detection of
UV absorbing or fluorescent tags.
According to the aim of the
study, three questions may be defined:
How
to separate and prepare ceramides ?
How to quantify a pool of ceramides ?
How to study the structure of ceramides ?
