Fatty acid: Difference between revisions
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== Basic Chemistry<br> == | == Basic Chemistry<br> == | ||
In fatty acids hydrophobic long carbon chain dominates in chemical properties the [[Hydrophilic|hydrophilic]] carboxyl group and gives the whole molecule [[Hydrophobic|hydrophobic]] character <ref>Charles E. Ophardt, 2003. Virtual Chembook. [online] Available at http://www.elmhurst.edu/~chm/vchembook/551fattyacids.html [Accessed 11 January 2011]</ref>. | In fatty acids hydrophobic long [[carbon|carbon]] chain dominates in chemical properties the [[Hydrophilic|hydrophilic]] [[carboxyl group|carboxyl group]] and gives the whole [[molecule|molecule]] [[Hydrophobic|hydrophobic]] character <ref>Charles E. Ophardt, 2003. Virtual Chembook. [online] Available at http://www.elmhurst.edu/~chm/vchembook/551fattyacids.html [Accessed 11 January 2011]</ref>. | ||
Naturally occurring fatty acids usually contain an even number of carbon atoms. The most common are 16 and 18 atoms long. The carbon skeleton is unbranched with a few exceptions. Longer carbon chain promotes stronger intermolecular interactions. This means that fatty acids with longer carbon chain have higher melting points (see Table 1). Some fatty acids contain double bonds in their alkyl chain. These are predominately in cis configuration, which results in "kinks" in the chain shape, in contrast with straight saturated acids. Effectively, straight acid fatty acids can "pack" closer together and therefore have higher melting points due to stronger molecular interactions (see Table 1) <ref>Jeremy M. Berg, John L. Tymoczko, Lubert Stryer, 2002. Biochemistry. 5th ed. New York: W. H. Freeman and Company</ref>. | Naturally occurring fatty acids usually contain an even number of [[carbon|carbon]] [[atom|atoms]]. The most common are 16 and 18 [[atom|atoms]] long. The [[carbon|carbon]] skeleton is unbranched with a few exceptions. Longer [[carbon|carbon]] chain promotes stronger intermolecular interactions. This means that fatty acids with longer [[carbon|carbon]] chain have higher melting points (see Table 1). Some fatty acids contain double bonds in their alkyl chain. These are predominately in cis configuration, which results in "kinks" in the chain shape, in contrast with straight saturated acids. Effectively, straight acid fatty acids can "pack" closer together and therefore have higher melting points due to stronger molecular interactions (see Table 1) <ref>Jeremy M. Berg, John L. Tymoczko, Lubert Stryer, 2002. Biochemistry. 5th ed. New York: W. H. Freeman and Company</ref>. | ||
Table 1 <ref>Charles E. Ophardt, 2003. Virtual Chembook. [online] Available at http://www.elmhurst.edu/~chm/vchembook/551fattyacids.html [Accessed 11 January 2011]</ref><ref>Jeremy M. Berg, John L. Tymoczko, Lubert Stryer, 2002. Biochemistry. 5th ed. New York: W. H. Freeman and Company</ref> | Table 1 <ref>Charles E. Ophardt, 2003. Virtual Chembook. [online] Available at http://www.elmhurst.edu/~chm/vchembook/551fattyacids.html [Accessed 11 January 2011]</ref><ref>Jeremy M. Berg, John L. Tymoczko, Lubert Stryer, 2002. Biochemistry. 5th ed. New York: W. H. Freeman and Company</ref> | ||
{| width="90%" border="1" cellpadding="1" cellspacing="1" | {| width="90%" border="1" cellpadding="1" cellspacing="1" | ||
| Line 17: | Line 17: | ||
! scope="col" | Melting Point (°C) | ! scope="col" | Melting Point (°C) | ||
|- | |- | ||
| Lauric Acid | | [[Lauric Acid|Lauric Acid]] | ||
| lauroyl | | lauroyl | ||
| dodecanoyl | | dodecanoyl | ||
| Line 23: | Line 23: | ||
| +44 | | +44 | ||
|- | |- | ||
| Myristic Acid | | [[Myristic Acid|Myristic Acid]] | ||
| myristoyl | | myristoyl | ||
| tetradecanoyl | | tetradecanoyl | ||
| Line 29: | Line 29: | ||
| +54 | | +54 | ||
|- | |- | ||
| Palmitic Acid | | [[Palmitic Acid|Palmitic Acid]] | ||
| palmitoyl | | palmitoyl | ||
| hexadecanoyl | | hexadecanoyl | ||
| Line 35: | Line 35: | ||
| +63 | | +63 | ||
|- | |- | ||
| Stearic Acid | | [[Stearic Acid|Stearic Acid]] | ||
| stearoyl | | stearoyl | ||
| octadecanoyl | | octadecanoyl | ||
| Line 41: | Line 41: | ||
| +70 | | +70 | ||
|- | |- | ||
| Oleic Acid | | [[Oleic Acid|Oleic Acid]] | ||
| oleoyl | | oleoyl | ||
| cis-9-octadecenoyl | | cis-9-octadecenoyl | ||
| Line 47: | Line 47: | ||
| +13 | | +13 | ||
|- | |- | ||
| Linoleic Acid | | [[Linoleic Acid|Linoleic Acid]] | ||
| linoleoyl | | linoleoyl | ||
| di-cis-9,12-octadecadienoyl | | di-cis-9,12-octadecadienoyl | ||
| Line 53: | Line 53: | ||
| -5 | | -5 | ||
|- | |- | ||
| Linolenic Acid | | [[Linolenic Acid|Linolenic Acid]] | ||
| linolenoyl | | linolenoyl | ||
| all-cis-9, 12,15-octadecatrienoyl | | all-cis-9, 12,15-octadecatrienoyl | ||
| Line 59: | Line 59: | ||
| -11 | | -11 | ||
|- | |- | ||
| Arachidonic Acid | | [[Arachidonic Acid|Arachidonic Acid]] | ||
| arachidonoyl | | arachidonoyl | ||
| all-cis-5,8,11,14-eicosatetraenoyl | | all-cis-5,8,11,14-eicosatetraenoyl | ||
| Line 65: | Line 65: | ||
| -50 | | -50 | ||
|} | |} | ||
== Nomenclature == | == Nomenclature == | ||
Systematic names for fatty acids are derived from their parent hydrocarbon names by adding the suffix -oic. Thereby, the fatty acid with 16 carbon atoms is called hexadecanoic acid. A monounsaturated fatty acid with 16 carbon atoms is called hexadecenoic acid. Fatty acids with 2 and 3 double bonds are called hexadecadienoic and hexadecatrienoic respectively. Trivial names are also commonly used (see Table 1). Greek letter Δ followed by a superscript number denotes the position of a double bond. Also, because at physiological pH fatty acids form ions, it is appropriate to reffer to them accordingly (see Table 1) <ref>Jeremy M. Berg, John L. Tymoczko, Lubert Stryer, 2002. Biochemistry. 5th ed. New York: W. H. Freeman and Company</ref>. | Systematic names for fatty acids are derived from their parent hydrocarbon names by adding the suffix -oic. Thereby, the fatty acid with 16 carbon atoms is called hexadecanoic acid. A monounsaturated fatty acid with 16 carbon atoms is called hexadecenoic acid. Fatty acids with 2 and 3 double bonds are called hexadecadienoic and hexadecatrienoic respectively. Trivial names are also commonly used (see Table 1). Greek letter Δ followed by a superscript number denotes the position of a double bond. Also, because at physiological pH fatty acids form ions, it is appropriate to reffer to them accordingly (see Table 1) <ref>Jeremy M. Berg, John L. Tymoczko, Lubert Stryer, 2002. Biochemistry. 5th ed. New York: W. H. Freeman and Company</ref>. <br> | ||
<br> | |||
== References <br> == | == References <br> == | ||
Revision as of 16:24, 11 January 2011
Fatty acids are carboxylic acids with carbon chain length ranging from 10 to 30 atoms.
Basic Chemistry
In fatty acids hydrophobic long carbon chain dominates in chemical properties the hydrophilic carboxyl group and gives the whole molecule hydrophobic character [1].
Naturally occurring fatty acids usually contain an even number of carbon atoms. The most common are 16 and 18 atoms long. The carbon skeleton is unbranched with a few exceptions. Longer carbon chain promotes stronger intermolecular interactions. This means that fatty acids with longer carbon chain have higher melting points (see Table 1). Some fatty acids contain double bonds in their alkyl chain. These are predominately in cis configuration, which results in "kinks" in the chain shape, in contrast with straight saturated acids. Effectively, straight acid fatty acids can "pack" closer together and therefore have higher melting points due to stronger molecular interactions (see Table 1) [2].
| Trivial Name | Trivial carboxylate name | Formal Name | Designation | Melting Point (°C) |
|---|---|---|---|---|
| Lauric Acid | lauroyl | dodecanoyl | 12:0 | +44 |
| Myristic Acid | myristoyl | tetradecanoyl | 14:0 | +54 |
| Palmitic Acid | palmitoyl | hexadecanoyl | 16:0 | +63 |
| Stearic Acid | stearoyl | octadecanoyl | 18:0 | +70 |
| Oleic Acid | oleoyl | cis-9-octadecenoyl | 18:1c Δ9 | +13 |
| Linoleic Acid | linoleoyl | di-cis-9,12-octadecadienoyl | 18:2cc Δ9,12 | -5 |
| Linolenic Acid | linolenoyl | all-cis-9, 12,15-octadecatrienoyl | 18:3ccc Δ9,12,15 | -11 |
| Arachidonic Acid | arachidonoyl | all-cis-5,8,11,14-eicosatetraenoyl | 20:4cccc Δ5,8,11,14 | -50 |
Nomenclature
Systematic names for fatty acids are derived from their parent hydrocarbon names by adding the suffix -oic. Thereby, the fatty acid with 16 carbon atoms is called hexadecanoic acid. A monounsaturated fatty acid with 16 carbon atoms is called hexadecenoic acid. Fatty acids with 2 and 3 double bonds are called hexadecadienoic and hexadecatrienoic respectively. Trivial names are also commonly used (see Table 1). Greek letter Δ followed by a superscript number denotes the position of a double bond. Also, because at physiological pH fatty acids form ions, it is appropriate to reffer to them accordingly (see Table 1) [5].
References
- ↑ Charles E. Ophardt, 2003. Virtual Chembook. [online] Available at http://www.elmhurst.edu/~chm/vchembook/551fattyacids.html [Accessed 11 January 2011]
- ↑ Jeremy M. Berg, John L. Tymoczko, Lubert Stryer, 2002. Biochemistry. 5th ed. New York: W. H. Freeman and Company
- ↑ Charles E. Ophardt, 2003. Virtual Chembook. [online] Available at http://www.elmhurst.edu/~chm/vchembook/551fattyacids.html [Accessed 11 January 2011]
- ↑ Jeremy M. Berg, John L. Tymoczko, Lubert Stryer, 2002. Biochemistry. 5th ed. New York: W. H. Freeman and Company
- ↑ Jeremy M. Berg, John L. Tymoczko, Lubert Stryer, 2002. Biochemistry. 5th ed. New York: W. H. Freeman and Company