the furanocoumarin o-methyltransferases , which transfer a methyl group from s-adenosyl-l-methionine ( sam ) to the 5- or 8-hydroxyls of linear furanocoumarins , were not retarded by 5- ( 3-carboxypropanamido ) -xanthotoxin ( cpax ) immobilized to ah-sepharose 4b , but addition of sam to the irrigant buffer led to complete retardation of both enzymes on this affinity system .
C0016859
furanocoumarins
C0025684
xanthotoxin