preferred_name: fumarate(in) + succinate(out) <=> fumarate(out) + succinate(in)
preferred_name_lc: fumarate(in) + succinate(out) <=> fumarate(out) + succinate(in)
label: fumarate(in) + succinate(out) <=> fumarate(out) + succinate(in)
label_lc: fumarate(in) + succinate(out) <=> fumarate(out) + succinate(in)