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