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