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Ceramides are a family of waxy lipid molecules. A ceramide is composed of sphingosine and a fatty acid joined by an amide bond. Ceramides are found in high concentrations within the cell membrane of eukaryotic cells, since they are component lipids that make up sphingomyelin, one of the major lipids in the lipid bilayer. [1]
The fundamental structure of a cerebroside is ceramide. Monoglycosyl and oligoglycosylceramides having a mono or polysaccharide bonded glycosidically to the terminal OH group of ceramide are defined as cerebrosides. Sphingosine is the main long-chain base present in ceramide. Galactosylceramide is the principal glycosphingolipid in brain tissue.
Sphingomyelin has been found to have a role in cell apoptosis by hydrolyzing into ceramide. Studies in the late 1990s had found that ceramide was produced in a variety of conditions leading to apoptosis. [14] It was then hypothesized that sphingomyelin hydrolysis and ceramide signaling were essential in the decision of whether a cell dies.
The long-chain bases, sometimes simply known as sphingoid bases, are the first non-transient products of de novo sphingolipid synthesis in both yeast and mammals. These compounds, specifically known as phytosphingosine and dihydrosphingosine (also known as sphinganine, [4] although this term is less common), are mainly C 18 compounds, with somewhat lower levels of C 20 bases. [5]
Also, because of its hydrophobic nature, ceramide readily flip-flops across membranes as supported by studies in membrane models and membranes from red blood cells (erythrocytes). [6] However, ceramide can possibly interact with other lipids to form bigger regions called microdomains which restrict its flip-flopping abilities.
In whole blood (g/cm 3) In plasma or serum (g/cm 3) Water: Solvent 0.81-0.86 0.93-0.95 Acetoacetate: Produced in liver 8-40 × 10 −7: 4-43 × 10 −7: Acetone: product of bodyfat breakdown 3-20 × 10 −6: Acetylcholine: Neurotransmitter of the parasympathetic nervous system: 6.6-8.2 × 10 −8: Adenosine triphosphate: Energy storage total 3. ...
A ganglioside is a molecule composed of a glycosphingolipid (ceramide and oligosaccharide) with one or more sialic acids (e.g. N-acetylneuraminic acid, NANA) linked on the sugar chain. NeuNAc, an acetylated derivative of the carbohydrate sialic acid, makes the head groups of gangliosides anionic at pH 7, which distinguishes them from globosides.
Acid sphingomyelinase is one of the enzymes that make up the sphingomyelinase (SMase) family, responsible for catalyzing the breakdown of sphingomyelin to ceramide and phosphorylcholine. [1] They are organized into alkaline, neutral, and acidic SMase depending on the pH in which their enzymatic activity is optimal.