Pyroglutamates

As pyroglutamate which are salts and esters of pyroglutamic referred. In order to be able to differentiate between the two groups of substances, the term pyroglutamic acid ester should better be used for the latter.

L-arginine-L-pyroglutamate [salt from the basic L -arginine as a cation (left) and the anion (right) of L -pyroglutamic acid]

Pyroglutamate are unusual amino acid - derivatives , in which the free amino group of glutamate by a ring-closing a lactam is formed. They are in proteins such as B. found in bacteriorhodopsin , but also as a free form in small proportions in plants, such as. B. Paprika fruits. N -terminal glutamines can spontaneously cyclize to pyroglutamates. This blocks the N terminus for sequencing by Edman degradation , which requires a free primary amino group. The enzyme pyroglutamate aminopeptidase can restore the free N terminus of a protein by cleaving the pyroglutamate.

Examples

• L-arginine-L-pyroglutamate C ₆ H ₁₄ N ₄ O ₂ · C ₅ H ₇ NO ₃ , CAS number: 56265-06-6

swell

• DN Podell, GN Abraham: A technique for the removal of pyroglutamic acid from the amino terminus of proteins using calf liver pyroglutamate amino peptidase. In: Biochem Biophys Res Commun . 81 (1), Mar 15, 1978, pp. 176-185.