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Aspartic acid (symbol Asp or D; [4] the ionic form is known as aspartate), is an α-amino acid that is used in the biosynthesis of proteins. [5] The L-isomer of aspartic acid is one of the 22 proteinogenic amino acids, i.e., the building blocks of proteins. D-aspartic acid is one of two D-amino acids commonly found in mammals.
The products usually are either alanine, aspartate or glutamate, since their corresponding alpha-keto acids are produced through metabolism of fuels. Being a major degradative aminoacid pathway, lysine , proline and threonine are the only three amino acids that do not always undergo transamination and rather use respective dehydrogenase.
Glutamic acid (symbol Glu or E; [4] the anionic form is known as glutamate) is an α-amino acid that is used by almost all living beings in the biosynthesis of proteins.It is a non-essential nutrient for humans, meaning that the human body can synthesize enough for its use.
Aspartate transaminase (AST) or aspartate aminotransferase, also known as AspAT/ASAT/AAT or (serum) glutamic oxaloacetic transaminase (GOT, SGOT), is a pyridoxal phosphate (PLP)-dependent transaminase enzyme (EC 2.6.1.1) that was first described by Arthur Karmen and colleagues in 1954.
A catalytic triad charge-relay system as commonly found in proteases. The acid residue (commonly glutamate or aspartate) aligns and polarises the base (usually histidine) which activates the nucleophile (often serine or cysteine, occasionally threonine). The triad reduces the pK a of the nucleophilic residue which then attacks the substrate.
Glutamate transporters also transport aspartate and are present in virtually all peripheral tissues, including the heart, liver, testes, and bone. They exhibit stereoselectivity for L-glutamate but transport both L-aspartate and D-aspartate. The EAATs are membrane-bound secondary transporters that superficially resemble ion channels. [1]
Animals must metabolize proteins to amino acids, at the expense of muscle tissue, when blood sugar is low. The preference of liver transaminases for oxaloacetate or alpha-ketoglutarate plays a key role in funneling nitrogen from amino acid metabolism to aspartate and glutamate for conversion to urea for excretion of nitrogen.
Since aspartate is an amino acid, an amino radical needs to be added to the oxaloacetate. This is supplied by glutamate, which in the process is transformed into alpha-ketoglutarate by the same enzyme. The second antiporter (AGC1 or AGC2) imports glutamate from the cytosol into the matrix and exports aspartate from the matrix to the cytosol.