a 5-hydroxyfurocoumarin + S-adenosyl-L-methionine = a 5-methoxyfurocoumarin + H(+) + S-adenosyl-L-homocysteine bergaptol + S-adenosyl-L-methionine = bergapten + S-adenosyl-L-homocysteine Inhibited by Cu(2+), Ni(2+) and Co(2+). Optimum pH is 8.0. Optimum temperature is 42 degrees Celsius. Up-regulated by Pmg elicitor. Belongs to the class I-like SAM-binding methyltransferase superfamily. Cation-independent O-methyltransferase family. COMT subfamily.