Aspartat

Aspartate, commonly referred to as aspartate or aspartic acid in its protonated form, is the deprotonated anion of aspartic acid. It is a negatively charged amino acid at physiological pH, containing two carboxyl groups and an amino group. In biology, the L-enantiomer is the form incorporated into proteins.

In metabolism, aspartate participates in several important reactions. It is interconverted with oxaloacetate by transaminases, a process that links amino acid metabolism to the citric acid cycle and gluconeogenesis. Aspartate also serves as a nitrogen donor in the urea cycle, where it condenses with citrulline to form argininosuccinate, aiding in the removal of excess nitrogen. Additionally, aspartate is a precursor for the synthesis of purine and pyrimidine nucleotides, which are essential for DNA and RNA production. It can be produced from oxaloacetate, making it a non-essential amino acid in humans.

Aspartate is found in the cytosol and mitochondria of cells and is utilized in a variety of tissues. In humans, it is present in proteins in the L-configuration, which is the form incorporated by ribosomes during protein synthesis. Dietary sources include protein-rich foods, which supply aspartate as part of larger amino acids.

Clinically, aspartate aminotransferase (AST) is an enzyme measured in blood tests as a marker of tissue damage. Elevated AST levels can indicate liver injury, myocardial infarction, or other tissue damage and are often interpreted alongside alanine aminotransferase (ALT).