Question 23.3: Identifying Complex Lipid Components A class of membrane lip......
Identifying Complex Lipid Components
A class of membrane lipids known as plasmalogens has the general structure shown here. Identify the component parts of this lipid and choose the terms that apply to it: phospholipid, glycerophospholipid, sphingolipid, glycolipid. Is it most similar to a phosphatidylethanolamine, a phosphatidylcholine, a cerebroside, or a ganglioside?
ANALYSIS Compare each part of the molecule with the basic components found in complex lipids and decide which lipid component the part resembles most. The molecule contains a phosphate group and thus is a phospholipid. The glycerol backbone of three carbon atoms bonded to three oxygen atoms is also present, so the compound is a glycerophospholipid, but one in which there is an ether linkage (—CH_2—O—CH\xlongequal[]{}CHR) in place of one of the ester linkages. The phosphate group is bonded to ethanolamine (HOCH_2CH_2NH_2). This compound is not a sphingolipid or a glycolipid because it is not derived from sphingosine; for the same reason it is not a cerebroside or a ganglioside. Except for the ether group in place of an ester group, the compound has the same structure as a phosphatidylethanolamine.
The terms that apply to this plasmalogen are phospholipids and glycerophospholipid. It has a structure nearly identical to phosphatidylethanolamine, so it is most similar to phosphatidylethanolamine.