Omega nomenclature, fatty acids

There is one nomenclature that is commonly used, particularly in news articles intended for the lay audience. It is useful to understand it. Here families of fatty acids are collected by designating where the first double bond occurs, starting at the methyl group (CH3) end of the molecule, frequently known as the omega (co) carbon atom. Thus, the omega-3 fatty acids look hke ... 

Using the omega nomenclature, the major classes of unsaturated fatty acids found in mammalian tissue are co-3, co-6 and co-9. They are not interconvertible (Figure 11.9). 

For nomenclature purposes, the carbonyl carbon of a fatty acid is assigned the number 1. The carbon next to the carbonyl is called the a-carbon (alpha carbon) and the carbon at the opposite end of the chain is called the W-carbon (omega carbon). The pof most fatty acids is around 4,5, so most fatty acids exist in their anion form in the cellular environment. 

Omega nomenclature, fatty acids, 639-640 Omeprazole, ulcer treatment, 87... 

Note the presence of a double bond at the third carbon atom from the end of the hydrocarbon tail. The omega system of nomenclature is based on numbering the double bonds from the last carbon in the fatty acid instead of the carbonyl group [the delta (A) system]. Omega is the last letter in the Greek alphabet. 

Additional nomenclature for the unsaturated fatty acids is used to identify the site of C=C units relative to the terminal methyl group (the omega end). Because the closest double bond to the methyl group in palmitoleic acid (96) is 7 carbon atoms away from the methyl, palmitoleic acid is called an omega-7 ((0-7 or n-7) fatty acid. For a-linolenic acid (99), the double bond closest to the methyl group is only 3 carbons away, so it is an omega-3 ((0-3 or n-3) fatty acid. Several other acids are suitably labeled. 

Fatty acid nomenclatures as follows The number before the colon represents the number of carbon atoms. The number after the colon represents the number of ois double bonds. The number following the omega represents the position of the first double bond measured from the methyl end of the molecule. It is assumed that all of the double bonds are methylene interrupted. 

In addition, categorising polyunsaturated fatty acids according to the position of the double bond away from the terminal methyl group is common in biological documents. The nomenclature n-x (or a>-x) means that the first double bond is located on carbon number x counting from the terminal methyl group. The omega notation is common in popular nutritional hterature. Linoleic acid is an example of a polyunsaturated fatty add of the n-6 series (3-8). A short notation for linoleic acid is 18 2n-6 (or 18 2 )-6). Similarly, we come across fatty acids of n-3 (or a>-3) series (3-9). 

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