Last review and update: July 16, 2020.
A short summary.
We took several notes on fatty acids classification and share them below.
The omega-reference system for fatty acids.
James Baggott (1):
The omega-reference system indicates the number of carbons, the number of double bonds and the position of the double bond closest to the omega carbon, counting from the omega carbon (which is numbered 1 for this purpose).
Use of Greek letters to designate carbons in fatty acids.
James Baggott (1):
The first carbon following the carboxyl carbon is the alpha carbon.
The second carbon following the carboxyl carbon is the beta carbon.
The last carbon in the chain, farthest from the carboxyl group, is the omega carbon.
Sometimes, carbons close to omega carbon are designated in relation to the latter. For example, the third from the end is “omega – 3”, or “omega minus 3”.
Useful schematic depictions of fatty acids.
The following figure from the article by Linus Pauling Institute (2) provides useful schematic depictions of fatty acids.
Examples of fatty acids with different number of double bonds.
Zero double bonds = saturated fatty acids.
2 or more double bonds = polyunsaturated fatty acids.
Names and Abbreviations of the Omega-6 and Omega-3 Fatty Acids by Linus Pauling Institute (2).
Tables and notes on fatty acids from Brondz, 2016 (3).
Brondz, 2016 (3):
Normal Saturated FFAs
Aliphatic FAs have the general formula H-(CH2)n-COOH, where n ranges from 0 to more than 40. Formic acid is the first member of the normal saturated FA homologous series (see Table 1).
Selected references:
1. James Baggott https://library.med.utah.edu/NetBiochem/FattyAcids/4_1c.html
Accessed on July 16, 2020.
2. Linus Pauling Institute.
https://lpi.oregonstate.edu/mic/other-nutrients/essential-fatty-acids
Accessed on July 16, 2020.
3. I. Brondz. LIPIDS, Fatty Acids. Encyclopedia of Analytical Science, 2005, Pages 76-88. https://doi.org/10.1016/B978-0-12-409547-2.13780-1