preferred_name: serotonin(out) + n H(+)(in) => serotonin(in) + n H(+)(out)
preferred_name_lc: serotonin(out) + n h(+)(in) => serotonin(in) + n h(+)(out)
label: serotonin(out) + n H(+)(in) => serotonin(in) + n H(+)(out)
label_lc: serotonin(out) + n h(+)(in) => serotonin(in) + n h(+)(out)