Occurrence
Dietary sources
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 : luncheon meats, sausage meat, wild game
Vegetable sources: sprouting seeds, oat flakes, avocado,
asparagus , young sugarcane, and molasses from sugar beets.
Chemical synthesis
Racemic aspartic acid can be synthesized from diethyl sodium phthalimido malonate, (C6H4(CO)2NC(CO2Et)2).
The major disadvantage of the above technique is that equimolar amounts of each enantiomer are made. Using biotechnology it is now possible to use immobilized enzymes to create just one type of enantiomer owing to their stereo specificity. 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 mM from 1 M.
History
Aspartic acid was first discovered in 1827 by Plisson, derived from asparagine, which had been isolated from asparagus juice in 1806, by boiling with a base.
Definition
ChEBI: The L-enantiomer of aspartic acid.
Aroma threshold values
Detection: 300 ppb
General Description
To request documentation for this product, please contact Customer Support and select ‘Product Documentation′. Please note that access to the documentation for this product requires a confidentiality disclosure agreement.
Biological Activity
Endogenous NMDA receptor agonist.
Biochem/physiol Actions
Principal neurotransmitter for fast synaptic excitation.
Synthesis
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 "semi aldehyde," O2CCH(NH2)CH2CHO. Asparagine is derived from aspartate via trans amidation :
-O2CCH(NH2)CH2CO2 - + G C (O)NH3+ O2CCH(NH2)CH2CONH3+ + GC(O)O
(where GC(O)NH2 and GC(O)OH are glutamine and glutamic acid, respectively).
Synthesis
Enzymatically, aspartic acid is reversibly synthesized by a transamination reaction between oxaloacetic acid and glutamic
acid in the presence of pyridoxal phosphate.
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, "Daspartic 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.
Other biochemical roles
Aspartate is also a metabolite in the urea cycle and participates in gluconeogenesis. It carries reducing equivalents in the malateaspartate shuttle, which utilizes the ready inter conversion 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.
;