squalene + S-adenosyl-L-methionine <=> 3-methyl-1,2-didehydro-2,3-dihydrosqualene + S-adenosyl-L-homocysteine + H(+)
squalene + s-adenosyl-l-methionine <=> 3-methyl-1,2-didehydro-2,3-dihydrosqualene + s-adenosyl-l-homocysteine + h(+)