Synthesis of Sphingolipids – Membrane Lipid Metabolism

by Kevin Ahern, PhD

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    00:00 The sphingolipids are another major components of cells. The sphingolipids, you can see, schematically on the screen. They contain a compound called sphingosine that we will see how it synthesizes in the minute and that sphingosine is linked to a fatty acid shown below in green.

    00:16 Now the attachment material point for the sphingolipids is the R that is shown on the right of this molecule.

    00:25 So sphingolipids are important, especially, for nerve tissue and brain.

    00:29 So very very prominent components.

    00:32 Sphingomyelin is one of the principle components of the myelin sheath of nerve cells.

    00:38 Sphingolipids are comprised of sphingosine, a fatty acid and a R group, as I said. So these will all come together to make the amphophilic substance that comprises the sphingolipids.

    00:50 Now the synthesis of these compounds starts with very simple materials it starts with the amino acid serine and palmitoyl-CoA.

    01:00 These two are joined together to make something like the sphingosine, as we shall see.

    01:07 So here is the amino acid serine and to that we combine a palmitoyl-CoA.

    01:11 The product to that reaction is dehydrosphingosine, you can see that we split of a CoA and carbon dioxide in the process of that.

    01:18 Now dehydrosphingosine can be converted to sphingosine.

    01:24 Now sphingosine is not directly converted into the sphingolipids, instead dehydrosphingosine is and it's dehydrosphingosine that is modified to become dihydrosphingonine, got a mouth full of names here.

    01:36 Dihydrosphingonine is reduced in some reactions, as you can see here, and a CoA is attached to the molecule.

    01:44 The product to that reaction is something called a ceramide.

    01:48 Now a ceramide is a building backbone for a sphingolipid, just like phosphatidic acid was a building backbone for sphingolipid.

    01:58 The R that you can see on the ceramide at the bottom is the R that is the upper portion of the figure on the screen.

    02:05 Now the R group attachment point is where the differentiating components of the sphingolipid will exist. If the R is phosphocholine or if the R is phosphoethanolamine we create one of a class of compounds called sphingomyelin. So as you can see sphingomyelin is not one compound but a variety of compounds.

    02:30 These sphingomyelins comprise the lipid bilayer of the myelin sheath of nerve cells so a very very important compounds.

    02:38 If R is a single sugar then we have created what we call a cerebroside.

    02:43 And like its name suggest, cerebroside are found commonly in brain tissue.

    02:47 If the R is a complex sugar then we create what's known as a ganglioside.

    02:55 This concludes the discussion of the metabolism of the sphingolipids and the glycerophospholipids.

    02:59 I hope that I have communicated to you that these compounds that are found in the lipid bilayer, like many compounds found in cells, have roots in very simple molecules, but drive very complex functions.

    About the Lecture

    The lecture Synthesis of Sphingolipids – Membrane Lipid Metabolism by Kevin Ahern, PhD is from the course Lipid Metabolism.

    Included Quiz Questions

    1. By adding a fatty acid to dihydrosphinganine.
    2. By adding a complex carbohydrate to dihydrosphinganine.
    3. By adding a sugar to dihydrosphinganine.
    4. By adding a phosphate to dihydrosphinganine.

    Author of lecture Synthesis of Sphingolipids – Membrane Lipid Metabolism

     Kevin Ahern, PhD

    Kevin Ahern, PhD

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