Homocysteine, a toxic 'natural' amino acid linked to the cause of heart disease,
Levomefolic acid (INN) (also known as 5-MTHF, l-methylfolate and 5-methyltetrahydrofolate) is the active form of folic acid used at the cellular level for DNA reproduction, the cysteine cycle and the regulation of homocysteine among other functions.
These folate-dependent biosynthetic reactions include the transfer of methyl groups from 5-methyltetrahydrofolate to homocysteine to form formyl groups from 10-formyltetrahydrofolate to N-formylmethionine in initiator tRNAs.
metK genes encode methionine adenosyltransferase, which synthesizes S-adenosyl methionine (SAM), and ahcY genes encode S-adenosylhomocysteine hydrolase, which degrade the related metabolite S-Adenosyl-L-homocysteine (SAH).