Fatty acid/ja: Difference between revisions

!Nomenclature

!Examples

!Explanation

!Trivial

|[[Palmitoleic acid]]

|'''[[Trivial name]]s''' (or '''common names''') are non-systematic historical names, which are the most frequent naming system used in literature. Most common fatty acids have trivial names in addition to their ''systematic names'' (see below). These names frequently do not follow any pattern, but they are concise and often unambiguous.

!Systematic

|[[Oleic acid|cis-9-octadec-9-enoic acid]]<br />[[Oleic acid|(9''Z'')-octadec-9-enoic acid]]

|'''[[Systematic name]]s''' (or '''[[International Union of Pure and Applied Chemistry|IUPAC]] names''') derive from the standard ''[[IUPAC nomenclature of organic chemistry|IUPAC Rules for the Nomenclature of Organic Chemistry]]'', published in 1979, along with a recommendation published specifically for lipids in 1977. [[#Numbering of the carbon atoms in a fatty acid|Carbon atom numbering]] begins from the [[carboxylic group|carboxylic]] end of the molecule backbone. [[Double bond]]s are labelled with [[cis-trans isomerism|''cis''-/''trans''-]] notation or ''[[E-Z notation|E]]''-/''[[E-Z notation|Z]]''- notation, where appropriate. This notation is generally more verbose than common nomenclature, but has the advantage of being more technically clear and descriptive.

|[[Linoleic acid|''cis''-Δ⁹, ''cis''-Δ¹² octadecadienoic acid]]

|In '''Δ^''x''''' (or '''delta-''x''''') '''nomenclature''', each double bond is indicated by Δ^''x'', where the double bond begins at the ''x''th carbon–carbon bond, [[#Numbering of the carbon atoms in a fatty acid|counting]] from [[carboxylic group|carboxylic]] end of the molecule backbone. Each double bond is preceded by a ''[[cis-trans isomerism|cis]]''- or ''[[cis-trans isomerism|trans]]''- prefix, indicating the configuration of the molecule around the bond. For example, [[linoleic acid]] is designated "''cis''-Δ⁹, ''cis''-Δ¹² octadecadienoic acid". This nomenclature has the advantage of being less verbose than systematic nomenclature, but is no more technically clear or descriptive.

!''n''−''x'' <br />(or ω−''x'')

|[[Omega-3 fatty acid|''n''−3]]<br />(or [[Omega-3 fatty acid|ω−3]])

|'''''n''−''x''''' ('''''n'' minus ''x'''''; also '''ω−''x''''' or '''omega-''x''''') '''nomenclature''' both provides names for individual compounds and classifies them by their likely biosynthetic properties in animals. A double bond is located on the ''x''^th carbon–carbon bond, [[#Numbering of the carbon atoms in a fatty acid|counting]] from the [[Methyl group|methyl]] end of the molecule backbone. For example, [[α-Linolenic acid|α-linolenic acid]] is classified as a [[omega-3 fatty acid|''n''−3]] or [[omega-3]] fatty acid, and so it is likely to share a biosynthetic pathway with other compounds of this type. The ω−''x'', omega-''x'', or "omega" notation is common in popular nutritional literature, but [[IUPAC nomenclature|IUPAC]] has deprecated it in favor of ''n''−''x'' notation in technical documents. The most commonly researched fatty acid biosynthetic pathways are [[omega-3 fatty acid|''n''−3]] and [[omega-6 fatty acid|''n''−6]].

!Lipid numbers

|18:3<br />[[α-Linolenic acid|18:3n3]]<br />[[α-Linolenic acid|18:3,&nbsp;''cis'',''cis'',''cis''-Δ⁹,Δ¹²,Δ¹⁵]]<br />[[α-Linolenic acid|18:3(9,12,15)]]

|'''Lipid numbers''' take the form ''C'':''D'', where ''C'' is the number of carbon atoms in the fatty acid and ''D'' is the number of double bonds in the fatty acid. If D is more than one, the double bonds are assumed to be interrupted by [[methylene bridge|{{chem|CH|2}} units]], ''i.e.'', at intervals of 3 carbon atoms along the chain. For instance, [[α-Linolenic acid|α-linolenic acid]] is an 18:3 fatty acid and its three double bonds are located at positions Δ⁹, Δ¹², and Δ¹⁵. This notation can be ambiguous, as some different fatty acids can have the same ''C'':''D'' numbers. Consequently, when ambiguity exists this notation is usually paired with either a Δ^''x'' or ''n''−''x'' term. For instance, although [[α-Linolenic acid|α-linolenic acid]] and [[gamma-Linolenic acid|γ-linolenic acid]] are both 18:3, they may be unambiguously described as 18:3n3 and 18:3n6 fatty acids, respectively. For the same purpose, IUPAC recommends using a list of double bond positions in parentheses, appended to the C:D notation. For instance, IUPAC recommended notations for α- and γ-linolenic acid are 18:3(9,12,15) and 18:3(6,9,12), respectively.