Aspartaatista

Aspartaatista refers to aspartate, the deprotonated form of aspartic acid, and to compounds and metabolic processes that involve aspartate. In physiological conditions aspartate carries a negative charge due to its side-chain carboxylate. It is one of the 20 standard amino acids and is encoded in genes as "D" in older nomenclatures, though in modern protein sequencing it is commonly represented as Asp.

Aspartate participates in protein synthesis as a constituent amino acid. Beyond incorporation into proteins, it serves as a key metabolic intermediate. It is involved in transamination reactions via aspartate aminotransferase (AST), which transfers amino groups between aspartate and oxaloacetate, linking amino acid and carbohydrate metabolism. The malate–aspartate shuttle uses aspartate to move reducing equivalents across the mitochondrial membrane, supporting cellular energy production. Aspartate is also a nitrogen donor in nucleotide biosynthesis, notably in the synthesis of pyrimidines, where aspartate combines with carbamoyl phosphate to form carbamoyl aspartate.

In the liver, aspartate participates in the urea cycle, providing nitrogen for argininosuccinate synthesis, via argininosuccinate synthetase. Aspartate also acts as an excitatory neurotransmitter in the central nervous system.

Dietary aspartate is obtained from protein-containing foods and is considered non-essential, as humans can synthesize it endogenously. Abnormal levels of enzymes such as AST in blood tests can indicate tissue damage, particularly of liver or heart.

Cross references: aspartate aminotransferase, malate–aspartate shuttle, argininosuccinate synthetase, pyrimidine biosynthesis.