The two essential fatty acids are omega 3 and omega 6, which are required for a good human health. However, the effects of the
ω-3 (omega-3) and
ω-6 (omega-6)
essential fatty acid
Essential fatty acids, or EFAs, are fatty acids that humans and other animals must ingest because the body requires them for good health but cannot synthesize them.
Only two fatty acids are known to be essential for humans: alpha-linolenic ac ...
s (EFAs) are characterized by their interactions. The interactions between these two fatty acids has a direct effect on the signaling paths and biological functions like inflammation, protein synthesis, neurotransmitters in our brain and metabolic pathways in a human body.
Arachidonic acid (AA) is a 20-carbon ω-6 essential fatty acid.
It sits at the head of the "arachidonic acid cascade" that initiates 20 different
signaling paths that control a wide array of biological functions, including
inflammation
Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molec ...
,
cell growth and the
central nervous system.
Most AA in the human body is derived from dietary
linoleic acid
Linoleic acid (LA) is an organic compound with the formula COOH(CH2)7CH=CHCH2CH=CH(CH2)4CH3. Both alkene groups are ''cis''. It is a fatty acid sometimes denoted 18:2 (n-6) or 18:2 ''cis''-9,12. A linoleate is a salt or ester of this acid.
L ...
(18:2 ω-6), found in
nuts,
seeds
A seed is an Plant embryogenesis, embryonic plant enclosed in a testa (botany), protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, includ ...
,
vegetable oils and
animal fat
Animal fats and oils are lipids derived from animals: oils are liquid at room temperature, and fats are solid. Chemically, both fats and oils are composed of triglycerides. Although many animal parts and secretions may yield oil, in commercial ...
s.
During inflammation, two other groups of dietary essential fatty acids form cascades that compete with the arachidonic acid cascade.
EPA (20:5 ω-3) provides the most important competing cascade. EPA is ingested from
oily fish
Oily fish are fish species with oil (fats) in soft tissues and in the coelomic cavity around the gut. Their fillets may contain up to 30% oil, although this figure varies both within and between species. Examples of oily fish include smal ...
, algae oil, or
alpha-linolenic acid
''alpha''-Linolenic acid (ALA), also known as α-Linolenic acid (from Greek ''alpha'' meaning "first" and ''linon'' meaning flax), is an ''n''−3, or omega-3, essential fatty acid. ALA is found in many seeds and oils, including flaxseed, waln ...
(derived from
walnuts
A walnut is the edible seed of a drupe of any tree of the genus ''Juglans'' (family Juglandaceae), particularly the Persian or English walnut, ''Juglans regia''.
Although culinarily considered a "nut" and used as such, it is not a true b ...
,
hemp oil
Hemp oil (hemp seed oil) is oil obtained by pressing hemp seeds. Cold pressed, unrefined hemp oil is dark to clear light green in color, with a nutty flavor. The darker the color, the grassier the flavour. It should not be confused with hash o ...
and
flax
Flax, also known as common flax or linseed, is a flowering plant, ''Linum usitatissimum'', in the family Linaceae. It is cultivated as a food and fiber crop in regions of the world with temperate climates. Textiles made from flax are known in ...
oil).
DGLA (20:3 ω-6) provides a third, less prominent cascade. It is derived from dietary
GLA (18:3 ω-6) found in
borage oil. These two parallel cascades soften the inflammatory-promoting effects of specific
eicosanoids
Eicosanoids are signaling molecules made by the enzymatic or non-enzymatic oxidation of arachidonic acid or other polyunsaturated fatty acids (PUFAs) that are, similar to arachidonic acid, around 20 carbon units in length. Eicosanoids are a sub-c ...
made from AA.
The diet from a century ago had much less ω-3 than the diet of early
hunter-gatherer
A traditional hunter-gatherer or forager is a human living an ancestrally derived lifestyle in which most or all food is obtained by foraging, that is, by gathering food from local sources, especially edible wild plants but also insects, fungi ...
s but also much less pollution than today
which evokes the inflammatory response. We can also look at the ratio of ω-3 to ω-6 in comparison of their diets. These changes have been accompanied by increased rates of many diseases – the so-called
diseases of civilization – that involve inflammatory processes. There is now very strong evidence
that several of these diseases are ameliorated by increasing dietary ω-3. There is also more preliminary evidence showing that dietary ω-3 can ease symptoms in several psychiatric disorders.
Eicosanoid series nomenclature
Eicosanoids are signaling molecules derived from the essential fatty acids (EFA); they are a major pathway by which the EFAs act in the body. There are four classes of eicosanoid and two or three series within each class.
The
plasma membranes of
cells contain
phospholipid
Phospholipids, are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typ ...
s, which are composed of a hydrophilic phosphate head and two hydrophobic
fatty acid
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, fr ...
tails. Some of these fatty acids are 20-carbon
polyunsaturated
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
The term often refers specifically to triglycerides (triple est ...
essential fatty acids – AA, EPA or DGLA. In response to a variety of inflammatory signals, these EFAs are cleaved out of the phospholipid and released as free fatty acids. Next, the EFA is oxygenated (by either of two pathways), then further modified, yielding the eicosanoids.
Cyclooxygenase
Cyclooxygenase (COX), officially known as prostaglandin-endoperoxide synthase (PTGS), is an enzyme (specifically, a family of isozymes, ) that is responsible for formation of prostanoids, including thromboxane and prostaglandins such as p ...
(COX) oxidation removes two C=C
double bonds
In chemistry, a double bond is a covalent bond between two atoms involving four bonding electrons as opposed to two in a single bond. Double bonds occur most commonly between two carbon atoms, for example in alkenes. Many double bonds exist betwee ...
, leading to the
TX,
PG and
PGI series.
Lipoxygenase
Lipoxygenases () are a family of (non-heme) iron-containing enzymes most of which catalyze the dioxygenation of polyunsaturated fatty acids in lipids containing a cis,cis-1,4- pentadiene into cell signaling agents that serve diverse roles as a ...
oxidation removes no C=C double bonds and leads to the
LK.
After oxidation, the eicosanoids are further modified, making a ''series''. Members of a series are differentiated by a letter and are numbered by the number of double bonds, which does not change within a series. For example, cyclooxygenase action upon
AA (with 4 double bonds) leads to the series-2
thromboxanes
Thromboxane is a member of the family of lipids known as eicosanoids. The two major thromboxanes are thromboxane A2 and thromboxane B2. The distinguishing feature of thromboxanes is a 6-membered ether-containing ring.
Thromboxane is named for its ...
(TXA
2, TXB
2... ) each with two double bonds. Cyclooxygenase action on EPA (with 5 double bonds) leads to the series-3 thromboxanes (TXA
3, TXB
3... ) each with three double bonds. There are exceptions to this pattern, some of which indicate
stereochemistry
Stereochemistry, a subdiscipline of chemistry, involves the study of the relative spatial arrangement of atoms that form the structure of molecules and their manipulation. The study of stereochemistry focuses on the relationships between stereo ...
(PGF
2α).
Table (1) shows these sequences for AA (20:4 ω-6). The sequences for
EPA (20:5 ω-3) and
DGLA (20:3 ω-6) are analogous.
All prostanoids are substituted
prostanoic acids.
Cyberlipid Center's Prostenoid page
illustrates the parent compound and the rings associated with each series–letter.
The
IUPAC
The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...
and the
IUBMB use the equivalent term Icosanoid.
Arachidonic acid cascade in inflammation
In the arachidonic acid cascade, dietary
linoleic acid
Linoleic acid (LA) is an organic compound with the formula COOH(CH2)7CH=CHCH2CH=CH(CH2)4CH3. Both alkene groups are ''cis''. It is a fatty acid sometimes denoted 18:2 (n-6) or 18:2 ''cis''-9,12. A linoleate is a salt or ester of this acid.
L ...
(18:2 ω-6) is desaturated and elongated to form arachidonic acid (and also other omega 6),
ester
In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glyceride ...
ified into a
phospholipid
Phospholipids, are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typ ...
in the
cell membrane.
Next, in response to many inflammatory
stimuli
A stimulus is something that causes a physiological response. It may refer to:
*Stimulation
**Stimulus (physiology), something external that influences an activity
**Stimulus (psychology), a concept in behaviorism and perception
*Stimulus (economi ...
, such as
air pollution
Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different type ...
,
smoking
Smoking is a practice in which a substance is burned and the resulting smoke is typically breathed in to be tasted and absorbed into the bloodstream. Most commonly, the substance used is the dried leaves of the tobacco plant, which have bee ...
,
second-hand smoke
Passive smoking is the inhalation of tobacco smoke, called secondhand smoke (SHS), or environmental tobacco smoke (ETS), by persons other than the intended "active" smoker. It occurs when tobacco smoke enters an environment, causing its inhalat ...
,
hydrogenated vegetable oils and other exogenous toxins;
phospholipase
A phospholipase is an enzyme that hydrolyzes phospholipids into fatty acids and other lipophilic substances. Acids trigger the release of bound calcium from cellular stores and the consequent increase in free cytosolic Ca2+, an essential step i ...
is generated and cleaves this phospholipid, releasing AA as a
free fatty acid
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, fr ...
. AA can then be oxygenated and then further modified to form
eicosanoid
Eicosanoids are signaling molecules made by the enzymatic or non-enzymatic oxidation of arachidonic acid or other polyunsaturated fatty acids (PUFAs) that are, similar to arachidonic acid, around 20 carbon units in length. Eicosanoids are a sub-c ...
s –
autocrine and
paracrine agents that bind
receptors
Receptor may refer to:
* Sensory receptor, in physiology, any structure which, on receiving environmental stimuli, produces an informative nerve impulse
*Receptor (biochemistry), in biochemistry, a protein molecule that receives and responds to a ...
on the cell or its neighbors to alert the immune system of the cell damage. Alternatively, AA can diffuse into the
cell nucleus
The cell nucleus (pl. nuclei; from Latin or , meaning ''kernel'' or ''seed'') is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, h ...
and interact with
transcription factor
In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The fun ...
s to control
DNA transcription
Transcription is the process of copying a segment of DNA into RNA. The segments of DNA transcribed into RNA molecules that can encode proteins are said to produce messenger RNA (mRNA). Other segments of DNA are copied into RNA molecules called ...
for
cytokine
Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autoc ...
s or other hormones.
Mechanisms of ω-3 eicosanoid action
The eicosanoids from AA generally promote inflammation. Those from
GLA (''via'' DGLA) and from EPA are generally less inflammatory, inactive, or even anti-inflammatory. (This generalization is qualified: an eicosanoid may be pro-inflammatory in one tissue and anti-inflammatory in another. ''See'' discussion of PGE
2 at Calder
[
* Invited review article, PUFA Newsletter.] or Tilley.
)
Figure (2) shows the ω-3 and -6 synthesis chains, along with the major eicosanoids from AA, EPA and DGLA.
Dietary ω-3 and GLA counter the inflammatory effects of AA's eicosanoids in three ways – displacement,
competitive inhibition
Competitive inhibition is interruption of a chemical pathway owing to one chemical substance inhibiting the effect of another by competing with it for binding or bonding. Any metabolic or chemical messenger system can potentially be affected b ...
and direct counteraction.
Displacement
Dietary ω-3 decreases tissue concentrations of AA.
Animal studies show that increased dietary ω-3 results in decreased AA in brain and other tissue.
[
* Who were in turn citing ] alpha-Linolenic acid
''alpha''-Linolenic acid (ALA), also known as α-Linolenic acid (from Greek ''alpha'' meaning "first" and ''linon'' meaning flax), is an ''n''−3, or omega-3, essential fatty acid. ALA is found in many seeds and oils, including flaxseed, waln ...
(18:3 ω-3) contributes to this by displacing
linoleic acid
Linoleic acid (LA) is an organic compound with the formula COOH(CH2)7CH=CHCH2CH=CH(CH2)4CH3. Both alkene groups are ''cis''. It is a fatty acid sometimes denoted 18:2 (n-6) or 18:2 ''cis''-9,12. A linoleate is a salt or ester of this acid.
L ...
(18:2 ω-6) from the elongase and
desaturase
A fatty acid desaturase is an enzyme that removes two hydrogen atoms from a fatty acid, creating a carbon/carbon double bond. These desaturases are classified as:
* Delta - indicating that the double bond is created at a fixed position from the ...
enzymes that produce AA. EPA inhibits
phospholipase
A phospholipase is an enzyme that hydrolyzes phospholipids into fatty acids and other lipophilic substances. Acids trigger the release of bound calcium from cellular stores and the consequent increase in free cytosolic Ca2+, an essential step i ...
A2's release of AA from the cell membrane.
Other mechanisms involving the transport of EFAs may also play a role.
The reverse is also true – high dietary linoleic acid decreases the body's conversion of α-linolenic acid to EPA. However, the effect is not as strong; the desaturase has a higher affinity for α-linolenic acid than it has for linoleic acid.
[
* " etary arachidonic acid enriches its circulating pool in humans; however, 20:5n-3 is not similarly responsive to dietary restriction."]
Competitive Inhibition
DGLA and EPA compete with AA for access to the cyclooxygenase and lipoxygenase enzymes. So the presence of DGLA and EPA in tissues lowers the output of AA's
eicosanoids
Eicosanoids are signaling molecules made by the enzymatic or non-enzymatic oxidation of arachidonic acid or other polyunsaturated fatty acids (PUFAs) that are, similar to arachidonic acid, around 20 carbon units in length. Eicosanoids are a sub-c ...
. For example, dietary GLA increases tissue DGLA and lowers TXB
2.
[
* GLA decreases triglycerides, LDL, increases HDL, decreases TXB2 and other inflammatory markers. Review article; human and rat studies.][
* IV Supplementation with gamma-linolenic acid increased serum GLA but did not increase the plasma percentage of arachidonic acid (rat study), decreased TXB2.] Likewise, EPA inhibits the production of series-2 PG and TX.
Although DGLA forms no LTs, a DGLA derivative blocks the transformation of AA to LTs.
[
* "DGLA itself cannot be converted to LTs but can form a 15-hydroxyl derivative that blocks the transformation of arachidonic acid to LTs. Increasing DGLA intake may allow DGLA to act as a competitive inhibitor of 2-series PGs and 4-series LTs and thus suppress inflammation."]
Counteraction
Some DGLA and EPA derived eicosanoids counteract their AA derived counterparts. For example, DGLA yields PGE
1, which powerfully counteracts PGE
2.
[
* " etary GLA increases the content of its elongase product, dihomo-gamma linolenic acid (DGLA), within cell membranes without concomitant changes in arachidonic acid (AA). Subsequently, upon stimulation, DGLA can be converted by inflammatory cells to 15-(S)-hydroxy-8,11,13-eicosatrienoic acid and prostaglandin E1. This is noteworthy because these compounds possess both anti-inflammatory and antiproliferative properties."] EPA yields the antiaggregatory prostacyclin PGI
3 It also yields the leukotriene LTB
5 which vitiates the action of the AA-derived LTB
4.
The paradox of dietary GLA
Dietary
oxidized
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...
linoleic acid
Linoleic acid (LA) is an organic compound with the formula COOH(CH2)7CH=CHCH2CH=CH(CH2)4CH3. Both alkene groups are ''cis''. It is a fatty acid sometimes denoted 18:2 (n-6) or 18:2 ''cis''-9,12. A linoleate is a salt or ester of this acid.
L ...
(LA, 18:2 ω-6) is inflammatory. In the body, LA is desaturated to form GLA (18:3 ω-6), yet dietary GLA is anti-inflammatory. Some observations partially explain this paradox: LA competes with
α-linolenic acid
''alpha''-Linolenic acid (ALA), also known as α-Linolenic acid (from Greek ''alpha'' meaning "first" and ''linon'' meaning flax), is an ''n''−3, or omega-3, essential fatty acid. ALA is found in many seeds and oils, including flaxseed, waln ...
, (ALA, 18:3 ω-3) for Δ6-desaturase, and thereby eventually inhibits formation of anti-inflammatory EPA (20:5 ω-3). In contrast, GLA does not compete for Δ6-desaturase. GLA's elongation product
DGLA (20:3 ω-6) competes with 20:4 ω-3 for the Δ5-desaturase, and it might be expected that this would make GLA inflammatory, but it is not, perhaps because this step isn't
rate-determining. Δ6-desaturase does appear to be the rate-limiting step; 20:4 ω-3 does not significantly accumulate in bodily lipids.
DGLA inhibits inflammation through both competitive inhibition and direct counteraction (see
above.) Dietary GLA leads to sharply increased DGLA in the white blood cells' membranes, where LA does not. This may reflect white blood cells' lack of desaturase. Supplementing dietary GLA increases serum DGLA without increasing serum AA.
It is likely that some dietary GLA eventually forms AA and contributes to inflammation. Animal studies indicate the effect is small.
The empirical observation of GLA's actual effects argues that DGLA's anti-inflammatory effects dominate.
Complexity of pathways
Eicosanoid signaling paths are complex.
It is therefore difficult to characterize the action of any particular eicosanoid.
For example, PGE
2 binds four receptors, dubbed EP
1–4.
Each is coded by a separate gene, and some exist in multiple
isoform
A protein isoform, or "protein variant", is a member of a set of highly similar proteins that originate from a single gene or gene family and are the result of genetic differences. While many perform the same or similar biological roles, some isof ...
s.
Each EP receptor in turn couples to a
G protein
G proteins, also known as guanine nucleotide-binding proteins, are a family of proteins that act as molecular switches inside cells, and are involved in transmitting signals from a variety of stimuli outside a cell to its interior. Their ac ...
.
The EP
2, EP
4 and one isoform of the EP
3 receptors couple to G
s.
This increases intracellular
cAMP and is anti-inflammatory.
EP
1 and other EP
3 isoforms couple to G
q.
This leads to increased intracellular calcium and is pro-inflammatory.
Finally, yet another EP
3 isoform couples to G
i, which both decreases cAMP and increases calcium.
Many immune-system cells express multiple receptors that couple these apparently opposing pathways.
Presumably, EPA-derived PGE
3 has a somewhat different effect of on this system, but it is not well-characterized.
The arachidonic acid cascade in the central nervous system (CNS)
The arachidonic acid cascade proceeds somewhat differently in the brain.
Neurohormone A neurohormone is any hormone produced and released by neuroendocrine cells (also called neurosecretory cells) into the blood. By definition of being hormones, they are secreted into the circulation for systemic effect, but they can also have a rol ...
s,
neuromodulator
Neuromodulation is the physiological process by which a given neuron uses one or more chemicals to regulate diverse populations of neurons. Neuromodulators typically bind to metabotropic, G-protein coupled receptors (GPCRs) to initiate a secon ...
s or
neurotransmitter
A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, any main body part or target cell, may be another neuron, but could also be a gland or muscle cell.
Neuro ...
s act as first messengers. They activate phospholipids to release AA from
neuron
A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozo ...
cell membranes as a free fatty acid. During its short lifespan, free AA may affect the activity of the neuron's
ion channel
Ion channels are pore-forming membrane proteins that allow ions to pass through the channel pore. Their functions include establishing a resting membrane potential, shaping action potentials and other electrical signals by gating the flow of ...
s and
protein kinase
A protein kinase is a kinase which selectively modifies other proteins by covalently adding phosphates to them (phosphorylation) as opposed to kinases which modify lipids, carbohydrates, or other molecules. Phosphorylation usually results in a fun ...
s. Or it may be metabolized to form eicosanoids,
epoxyeicosatrienoic acid
The epoxyeicosatrienoic acids or EETs are signaling molecules formed within various types of cells by the metabolism of arachidonic acid by a specific subset of Cytochrome P450 enzymes termed cytochrome P450 epoxygenases. These nonclassic eicosa ...
s (EETs),
neuroprotectin
Neuroprotectin D1 (NPD1) (10''R'',17''S''-dihydroxy-4''Z'',7''Z'',11''E'',13''E'',15''Z'',19''Z''-docosahexaenoic acid) also known as Protectin D1 (PD1) is a docosanoid derived from the polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA) ...
D or various
endocannabinoids
Cannabinoids () are several structural classes of compounds found in the cannabis plant primarily and most animal organisms (although insects lack such receptors) or as synthetic compounds. The most notable cannabinoid is the phytocannabinoid tet ...
(
anandamide and its analogs.)
The actions of eicosanoids within the brain are not as well characterized as they are in inflammation. It is theorized that they act within the neuron as
second messengers controlling presynaptic inhibition and the activation of
protein kinase
A protein kinase is a kinase which selectively modifies other proteins by covalently adding phosphates to them (phosphorylation) as opposed to kinases which modify lipids, carbohydrates, or other molecules. Phosphorylation usually results in a fun ...
C. They also act as paracrine mediators, acting across synapses to nearby cells. Although detail on the effects of these signals is scant, (Piomelli, 2000) comments
Neurons in the CNS are organized as interconnected groups of functionally related cells (e.g., in sensory systems). A diffusible factor released from a neuron into the interstitial fluid
In cell biology, extracellular fluid (ECF) denotes all body fluid outside the cells of any multicellular organism. Total body water in healthy adults is about 60% (range 45 to 75%) of total body weight; women and the obese typically have a lower ...
, and able to interact with membrane receptors on adjacent cells, would be ideally used to "synchronize" the activity of an ensemble of interconnected neural cells. Furthermore, during development and in certain forms of learning, postsynaptic cells may secrete regulatory factors which diffuse back to the presynaptic component, determining its survival as an active terminal, the amplitude of its sprouting, and its efficacy in secreting neurotransmitters—a phenomenon known as retrograde regulation. The participation of arachidonic acid metabolites in retrograde signaling and in other forms of local modulation of neuronal activity has been proposed.
The EPA and DGLA cascades are also present in the brain and their eicosanoid metabolites have been detected. The ways in which these differently affect mental and neural processes are not nearly as well characterized as are the effects in inflammation.
Further discussion
Figure 2 shows two pathways from EPA to
DHA, including the exceptional
Sprecher's shunt.
5-LO acts at the fifth carbon from the
carboxyl group.
Other lipoxygenases—8-LO, 12-LO and 15-LO—make other eicosanoid-like products.
To act, 5-LO uses the nuclear-membrane
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. ...
5-lipoxygenase-activating protein
Arachidonate 5-lipoxygenase-activating protein also known as 5-lipoxygenase activating protein, or FLAP, is a protein that in humans is encoded by the ''ALOX5AP'' gene.
Function
FLAP is necessary for the activation of 5-lipoxygenase and theref ...
(FLAP), first to a
hydroperoxyeicosatetraenoic acid (HPETE), then to the first leukotriene, LTA.
See also
*
Essential fatty acid
Essential fatty acids, or EFAs, are fatty acids that humans and other animals must ingest because the body requires them for good health but cannot synthesize them.
Only two fatty acids are known to be essential for humans: alpha-linolenic ac ...
*
Omega-3 fatty acid
Omega−3 fatty acids, also called Omega-3 oils, ω−3 fatty acids or ''n''−3 fatty acids, are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond, three atoms away from the terminal methyl group in their che ...
*
Omega-6 fatty acid
Omega-6 fatty acids (also referred to as ω-6 fatty acids or ''n''-6 fatty acids) are a family of polyunsaturated fatty acids that have in common a final carbon-carbon double bond in the ''n''-6 position, that is, the sixth bond, counting from ...
*
Ratios of Omega 3 to Omega 6 in different foods
*
Eicosanoid
Eicosanoids are signaling molecules made by the enzymatic or non-enzymatic oxidation of arachidonic acid or other polyunsaturated fatty acids (PUFAs) that are, similar to arachidonic acid, around 20 carbon units in length. Eicosanoids are a sub-c ...
*
Docosanoid
In biochemistry, docosanoids are signaling molecules made by the metabolism of twenty-two-carbon fatty acids (EFAs), especially the omega-3 fatty acid, Docosahexaenoic acid (DHA) (i.e. 4''Z'',7''Z'',10''Z'',13''Z'',16''Z'',19''Z''-docosahexaenoic a ...
References
{{Reflist, 30em
Fatty acids
Eicosanoids
Docosanoids
Immune system
ca:Àcids grassos essencials#Interacció d'àcids grassos essencials