Figure 4.

Nicotianamine synthase activity after expression in E. coli. (A) Nicotianamine is synthesized by nicotianamine synthase by using three molecules of S-adenosyl methionine. (B) Nicotianamine synthase activity was assayed by using radio-labeled S-adenosyl methionine and TLC. Extracts from recombinant E. coli strains carrying the mutant allele from tomato (lanes 1 and 2) and the wild-type allele from tomato (lane 3) were used. Lane 4, nicotianamine synthase activity of the cloned barley nicotianamine synthase gene. Lane 5, extracts from an E. coli strain carrying only the cloning vector. The position of the nicotianamine product is indicated by arrows.