Since the number, type and position of the fatty acid as well as the type of headgroup can be varied modularly, there is a very large number of different phospholipids in nature. Examples are POPC, 1-palmitoyl-2-oleoylphosphatidylcholine (IUPAC: 1-palmitoyl-2-oleoyl- sn-glycero-3-phosphocholine) or DOPE, 1,2-dioleoylphosphatidylethanolamine (IUPAC: 1,2-dioleoyl- sn-glycero-3-phosphoethanolamine). The International Union of Pure and Applied Chemistry (IUPAC) instead uses “ glycero-phospho-alcohol”. The number of fatty acids could be 'mono' or 'di', the fatty acids are described as, e.g., oleoyl or palmitoyl (coming from oleic acid and palmitic acid, respectively), 'phosphatidyl' describes the backbone of the phospholipid molecule which encompasses glycerol, further esterified with one or two fatty acid and a phosphate group, and finally the alcohol is mentioned as described above.
In scientific literature, synthetic phospholipids are named in an abbreviated way according to “ number of the position of fatty acids-type of fatty acid-phosphatidyl-alcohol”. The phospholipid may have two esterified fatty acids and are called diacyl-phospholipids, whereas phospholipids with one fatty acid are called monoacylphospholipids or lyso-phospholipids. 1) The systematic designation of, for example, phosphatidic acid (PA) is 1,2-diacyl- sn-glycero-3-phosphate, where “ sn” means stereospecific numbering or stereo-specifically numbered, i.e., the carbon atom that appears on top in the Fischer projection showing a vertical carbon chain with the hydroxyl group at carbon-2 to the left is designated as C-1. The remaining sn-3 position is esterified with phosphoric acid which, in turn, is esterified with a short-chain alcohol of varying chemical structure forming the hydrophilic headgroup of the phospholipid (illustrated by a blue ball, see Figure 1). The sn-1 and sn-2 positions of the glycerol backbone are esterified with fatty acids of varying length and degree of saturation (illustrated in the symbolic presentations of phospholipids by yellow sticks). Phospholipids are amphiphilic, which means they "love" both water and fat, and consist of a hydrophilic as well as a lipophilic moiety. In addition, they are involved in several cellular processes and used as excipient in various pharmaceutical formulations. Arranged as a lipid bilayer, phospholipids play a significant role in the structure and functionality of biological membranes. They are of natural occurrence and the main components in cellular membranes.
Phospholipids are unique and versatile molecules. In this article, we give an answer to the question "What are phospholipids?" and explain the various phospholipid types. There are different types of phospholipids.
0 kommentar(er)
