Effect of ceramide N-acyl chain and polar headgroup structure on the properties of ordered lipid domains (lipid rafts).

Ceramides are sphingolipids that greatly stabilize ordered membrane domains (lipid rafts), and displace cholesterol from them. Ceramide-rich rafts have been implicated in diverse biological processes. Because ceramide analogues have been useful for probing the biological function of ceramide, and may have biomedical applications, it is important to characterize how ceramide structure affects membrane properties, including lipid raft stability and composition.

Site-specific cleavage--a model system for the identification of lipid-modified glutamate residues in proteins.

Numerous proteins are modified post-translationally after their biosynthesis at the ribosomes of the cell. One such modification, only poorly characterized to date, is the formation of lipid esters of glutamate side chains in the skin proteins of land-living mammals; here a subset of very long chain fatty acids, ceramides and/or glucosylceramides, are bound through their omega-hydroxy groups to structural proteins of the so-called "cornified envelope" in the outermost layer of the skin, the stratum corneum. We report an approach for the identification of proteins containing ester-modified glutamic acid residues and the determination of their positions within the peptide sequence, designed for mass spectrometric investigation of human skin proteins.

(4S,5S)-4-[(1R)-1,2-Dihydroxyethyl]-5-tridecyl-1,3-oxazolidin-2-one.

The title compound, C(18)H(35)NO(4), is a new bioactive amphiphilic lipid with a cis-substituted 1,3-oxazolidin-2-one head group. In the crystal structure, the molecules form intercalating bilayers in which the oxazolidinone head groups are joined together by hydrogen bonds into chains.