Homocysteine: Activity Assays

Homocysteine is a chemical compound with the formula HSCH2CH2CH(NH2)CO2H. It is a homologue of the naturally-occurring amino acid cysteine, differing in that its side-chain contains an additional methylene (-CH2-) group before the thiol (-SH) group. Alternatively, Homocysteine can be derived from methionine by removing the latter's terminal C methyl group. Elevations of Homocysteine also occur in the rare hereditary disease homocystinuria and in methylene-tetrahydrofolate-reductase deficiency. The latter is quite common and usually goes unnoticed, although there are reports that thrombosis and cardiovascular disease occurs more often in people with elevated Homocysteine.