Homocysteine is a non-proteogenic amino acid synthesized intracellularly by removal of the N-methyl group from the essential amino acid methionine. Homocysteine is exported from cells into the blood, where it exists mainly as an oxidized disulfide species, either as a dimer or bound to cysteine residues of serum proteins. The reduced form of homocysteine (`free' homocysteine) can be metabolized into cysteine via the transsulfuration pathway; however, it can also undergo intramolecular cyclization, forming the highly reactive pro-oxidant homocysteine thiolactone. Subsequent N-homocysteinylation of protein lysine residues by the reactive thiolactone disrupts protein conformation, leading to formation of cytotoxic protein aggregates. Homocyste
Size
100 assays
Concentration
n/a
Applications
Estimation of Homocysteine in various biological samples