What is "aspartic acid"

n. (context amino acid English) A nonessential amino acid, L-α-amino-succinic acid, (C₄H₇NO₄), found in animal protein and in sugar beet etc.

n. a crystalline amino acid found in proteins and occurring naturally in sugar beets and sugar cane

Aspartic acid (abbreviated as Asp or D; encoded by the codons [GAU and GAC]), also known as aspartate, is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH form under biological conditions), an α-carboxylic acid group (which is in the deprotonated −COO form under biological conditions), and a side chain CHCOOH. Under physiological conditions in proteins the sidechain usually occurs as the negatively charged aspartate form, −COO. It is semi-essential in humans, meaning the body can synthesize it from oxaloacetate.

In proteins aspartate sidechains are often hydrogen bonded, often as asx turns or asx motifs, which often occur at the N-termini of alpha helices.

Asp's L-isomer is one of the 23 proteinogenic amino acids, i.e., the building blocks of proteins. Asp (and glutamic acid) is classified as acidic, with a pK of 3.9, however in a peptide this is highly dependent on the local environment (as with all amino acids), and could be as high as 14. Asp is pervasive in biosynthesis.

-aspartic acid is one of the two main ingredients of the artificial sweetener aspartame, along with - phenylalanine.