Trivial Nomenclature of Fatty Acids and Phospholipids The ‘trivial’ (common) names of the common fatty acids that you should know are as follows:

Trivial Name Trivial Name Formal Name Shorthand (Fatty Acid) (Acyl Chain) (Acyl Chain) Designation Lauric Acid lauroyl dodecanoyl 12:0 Myristic Acid myristoyl tetradecanoyl 14:0 Palmitic Acid palmitoyl hexadecanoyl 16:0 Stearic Acid stearoyl octadecanoyl 18:0

Oleic Acid oleoyl cis-9-octadecenoyl 18:1c Δ9 Linoleic Acid linoleoyl di-cis-9,12-octadecadienoyl 18:2cc Δ9,12 Linolenic Acid linolenoyl all-cis-9, 12,15-octadecatrienoyl 18:3ccc Δ9,12,15 Arachidonic Acid arachidonoyl all-cis-5,8,11,14-eicosatetraenoyl 20:4cccc Δ5,8,11,14

Phospholipids are named in the trivial system as follows: (1) The basic building block, a 1,2-diacyl-sn-glycero-3-phospho- group (see below), is termed an L-α-1,2-diacylphosphatidyl residue:

R1 O CH2 O R2 O CH _ O O O

H2C P O O

To name the phospholipid completely in the trivial system, we must provide: (a) the trivial names of the fatty acyl chains (with an -oyl ending); and (b) the name of the polar alcohol which is joined to the phosphoryl group.

The full name is then assembled as follows if the 1- and 2-position acyl chains are different:

L-α-1-(acyl)-2-(acyl)-phosphatidyl-[alcohol] or, if the 1- and 2-position fatty acyl chains are the same:

L-α-1,2-di[acyl]-phosphatidyl-[alcohol] or, if there is no polar alcohol attached,

L-α-1-(acyl)-2-(acyl)-phosphatidic acid (or 1,2-diacylphosphatidic acid if the chains are the same).

Examples

CH3(CH2)10COO CH2 _ CH3(CH2)12COO CH O O

+ H2C P N(CH3)3 A O O

trans CH3(CH2)7CH=CH(CH2)7COO CH2 _ CH3(CH2)7CH=CH(CH2)7COO CH O O trans H2C P B O O

CH3(CH2)12COO CH2 _ CH3(CH2)4CH=CHCH2CH=CH(CH2)7COO CH O O cis cis + H2C P NH3 O O C

Trivial Names of above lipids: A - L-α-1-lauroyl-2-myristoyl phosphatidylcholine

B - L-α-1,2-dielaidoyl phosphatidic acid

C - L-α-1-myristoyl-2-linoleoyl phosphatidylethanolamine

Exercises (1) Draw the structures of the following lipids:

(a) 1-palmitoyl-2-oleoyl phosphatidylserine

(b) 1,2-dimyristoyl phosphatidic acid (c) 1,2-dipalmitoyl phosphatidylcholine

(d) 1-stearoyl-2-oleoyl phosphatidylethanolamine

(2) Name the following lipids: Answers to Nomenclature Problems

1. (in order (a) - (d)):

2. (a) 1-stearoyl-2-linoleoyl phosphatidylcholine (b) 1,2-dioleoyl phosphatidylserine (c) 1,2-dipalmitoyl phosphatidylethanolamine (d) 1-palmitoyl-2-linolenoyl phosphatidic acid