Isocitric acid is a
structural isomer of
citric acid
Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in ...
. Since citric acid and isocitric acid are structural isomers, they share similar physical and chemical properties. Due to these similar properties, it is difficult to separate the isomers.
Salts and
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. Glycerides a ...
s of isocitric acid are known as isocitrates. The isocitrate anion is a substrate of the
citric acid cycle
The citric acid cycle (CAC)—also known as the Krebs cycle or the TCA cycle (tricarboxylic acid cycle)—is a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and protein ...
. Isocitrate is formed from
citrate
Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in the ...
with the help of the
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 ...
aconitase, and is acted upon by
isocitrate dehydrogenase
Isocitrate dehydrogenase (IDH) () and () is an enzyme that catalyzes the oxidative decarboxylation of isocitrate, producing alpha-ketoglutarate (α-ketoglutarate) and CO2. This is a two-step process, which involves oxidation of isocitrate (a s ...
.
Isocitric acid is commonly used as a marker to detect the authenticity and quality of fruit products, most often citrus juices. In authentic orange juice, for example, the ratio of citric acid to
D-isocitric acid is usually less than 130. An isocitric acid value higher than this may be indicative of fruit juice adulteration.
Isocitric acid has largely been used as a biochemical agent due to limited amounts.
However, isocitric acid has been shown to have pharmaceutical and therapeutic effects. Isocitric acid has been shown to effectively treat iron deficient anemia.
Additionally, isocitric acid could be used to treat
Parkinson's disease
Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms becom ...
.
''
Yarrowia lipolytica
''Yarrowia'' is a fungal genus in the family Dipodascaceae. For a while the genus was monotypic, containing the single species ''Yarrowia lipolytica'', a yeast that can use unusual carbon sources, such as hydrocarbons. This has made it of interes ...
'' can be used to produce isocitric acid and is inexpensive compared to other methods. Furthermore, other methods produce unequal amounts of citric acid to isocitric acid ratio, mostly producing citric acid. Use of ''Yarrowia lipolytica'' produces a better yield, making equal amounts of citric acid to isocitric acid.
Interactive pathway map
See also
*
Citric Acid
Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in ...
*
Tartaric Acid
Tartaric acid is a white, crystalline organic acid that occurs naturally in many fruits, most notably in grapes, but also in bananas, tamarinds, and citrus. Its salt, potassium bitartrate, commonly known as cream of tartar, develops naturally ...
*
Malic Acid
Malic acid is an organic compound with the molecular formula . It is a dicarboxylic acid that is made by all living organisms, contributes to the sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms ( ...
References
Alpha hydroxy acids
Tricarboxylic acids
Citric acid cycle compounds
Aldols
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