precorrin-2 + 2 S-adenosyl-L-homocysteine + H(+) => uroporphyrinogen III + 2 S-adenosyl-L-methionine
precorrin-2 + 2 s-adenosyl-l-homocysteine + h(+) => uroporphyrinogen iii + 2 s-adenosyl-l-methionine