S-adenosyl-L-homocysteine amino-acid zwitterion S-adenosyl-L-homocysteine zwitterion CHEBI:57856 5'-S-[(3S)-3-azaniumyl-3-carboxylatopropyl]-5'-thioadenosine MetaCyc:ADENOSYL-HOMO-CYS Wikipedia:S-Adenosyl-L-homocysteine Zwitterionic form of S-adenosyl-L-homocysteine arising from migration of a proton from the carboxy group to the alpha-amino group; major species at pH 7.3. S-adenosyl-L-homocysteine