cysteinic

Cysteinic is a rare biochemical adjective meaning “of or relating to cystine.” Cystine is the oxidized, disulfide-linked form of cysteine, the sulfur-containing amino acid found in proteins. The adjective is principally encountered in the older or alternative name cysteinic acid, now more commonly written cysteic acid, for an oxidation product in which cysteine’s thiol group is further oxidized to a sulfonic acid group. Cysteinic therefore describes chemical relationships to cystine rather than naming an amino acid, a radical, or a protein in general. Its use is confined largely to chemistry, biochemistry, nutrition, and analytical literature. Recognizing it is useful in older scientific writing and in material about protein oxidation, where cysteic and cysteinic can occur in close proximity, but specialists distinguish the acid’s identity from the adjective cysteinic and from the amino acids cysteine and cystine themselves.

Of or relating to cystine, especially to the oxidation product historically known as cysteinic acid.

Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.

Where does cysteinic come from?

Cysteinic was formed in English by adding the suffix -ic to cystine, giving it the sense “of or relating to cystine.” Cystine belongs to a family of biochemical names ultimately associated with Greek kystē (κύστη), meaning “bladder,” through the historical name cystine, originally applied to a urinary concretion. In modern usage, cysteinic is a specialized adjective associated particularly with the older term cysteinic acid.

How cysteinic is actually used

A specialist biochemical adjective, chiefly associated with older scientific terminology. It is uncommon outside chemistry, biochemistry, nutrition, and analytical research.

Easily confused with cysteinic

Words and phrases paired with cysteinic