Trivial: Aspartic acid
Systematic: 2-Aminobutanedioic acid
Aminosuccinic acid, asparagic acid, asparaginic acid
|Molar mass||133.10 g·mol−1|
|Melting point||270 °C (518 °F; 543 K)|
|Boiling point||324 °C (615 °F; 597 K) (decomposes)|
|Safety data sheet||See: data page|
|Supplementary data page|
|Refractive index (n),
Dielectric constant (εr), etc.
|UV, IR, NMR, MS|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is: / ?)(|
Aspartic acid (abbreviated as Asp or D) is an α-amino acid with the chemical formula HOOCCH(NH2)CH2COOH. The carboxylate anion and salts of aspartic acid are known as aspartate. The L-isomer of aspartate is one of the 23 proteinogenic amino acids, i.e., the building blocks of proteins. Its codons are GAU and GAC.
Aspartic acid is, together with glutamic acid, classified as an acidic amino acid with a pKa of 3.9, however in a peptide the pKa is highly dependent on the local environment. A pKa as high as 14 is not at all uncommon. Aspartate is pervasive in biosynthesis. As with all amino acids, the presence of acid protons depends on the residue's local chemical environment and the pH of the solution.
Forms and nomenclature
There are two forms or enantiomers of aspartic acid. The name "aspartic acid" can refer to either enantiomer or a mixture of two. Of these two forms, only one, "L-aspartic acid", is directly incorporated into proteins. The biological roles of its counterpart, "D-aspartic acid" are more limited. Where enzymatic synthesis will produce one or the other, most chemical syntheses will produce both forms, "DL-aspartic acid," known as a racemic mixture.
Aspartate is non-essential in mammals, being produced from oxaloacetate by transamination. It can also be generated from ornithine and citrulline in the urea cycle. In plants and microorganisms, aspartate is the precursor to several amino acids, including four that are essential for humans: methionine, threonine, isoleucine, and lysine. The conversion of aspartate to these other amino acids begins with reduction of aspartate to its "semialdehyde," O2CCH(NH2)CH2CHO. Asparagine is derived from aspartate via transamidation:
- -O2CCH(NH2)CH2CO2- + GC(O)NH3+ O2CCH(NH2)CH2CONH3+ + GC(O)O
Other biochemical roles
Aspartate is also a metabolite in the urea cycle and participates in gluconeogenesis. It carries reducing equivalents in the malate-aspartate shuttle, which utilizes the ready interconversion of aspartate and oxaloacetate, which is the oxidized (dehydrogenated) derivative of malic acid. Aspartate donates one nitrogen atom in the biosynthesis of inosine, the precursor to the purine bases. In addition, aspartic acid acts as hydrogen acceptor in a chain of ATP synthase.
Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles. [§ 1]
- The interactive pathway map can be edited at WikiPathways: "GlycolysisGluconeogenesis_WP534".
Aspartic acid is not an essential amino acid, which means that it can be synthesized from central metabolic pathway intermediates in humans. Aspartic acid is found in:
- Animal sources: oysters, luncheon meats, sausage meat, wild game
- Vegetable sources: sprouting seeds, oat flakes, avocado, asparagus, young sugarcane, and molasses from sugar beets.
- Dietary supplements, either as aspartic acid itself or salts (such as magnesium aspartate)
- The sweetener aspartame (brands: NutraSweet, Equal, Canderel, etc.)
The major disadvantage of the above technique is that equimolar amounts of each enantiomer are made. Using biotechnology it is now possible to use immobilised enzymes to create just one type of enantiomer owing to their stereospecificity. Aspartic acid is made synthetically using ammonium fumarate and aspartase from E.coli, E.coli usually breaks down the aspartic acid as a nitrogen source but using excess amounts of ammonium fumarate a reversal of the enzyme's job is possible, and so aspartic acid is made to very high yields, 98.7 mmol from 1 mol.
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- GMD MS Spectrum
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