Allysine is a derivative of
lysine that features a formyl group in place of the terminal amine. The free amino acid does not exist, but the allysine residue does. It is produced by aerobic oxidation of lysine residues by the enzyme
lysyl oxidase. The transformation is an example of a
post-translational modification. The
semialdehyde form exists in equilibrium with a cyclic derivative.[1]
Allysine is involved in the production of
elastin and
collagen.[2] Increased allysine concentration in tissues has been correlated to the presence of fibrosis.[3]
Allysine residues react with sodium 2-naphthol-6-sulfonate to produce a
fluorescent bis-naphtol-allysine product.[4] In another assay, allysine-containing proteins are reduced with sodium borohydride to give a peptide containing the 6-hydroxynorleucine (6-hydroxy-2-amino
caproic acid) residue, which (unlike allysine) is stable to proteolysis.[1]
Further reading
Luna C, Estévez M (January 2019). "Formation of allysine in β-lactoglobulin and myofibrillar proteins by glyoxal and methylglyoxal: Impact on water-holding capacity and in vitro digestibility". Food Chemistry. 271: 87–93.
doi:
10.1016/j.foodchem.2018.07.167.
PMID30236745.
S2CID52309183.