preferred_name: histidine => urocanate + NH4+ (Xenopus tropicalis)
preferred_name_lc: histidine => urocanate + nh4+ (xenopus tropicalis)
label: histidine => urocanate + NH4+ (Xenopus tropicalis)
label_lc: histidine => urocanate + nh4+ (xenopus tropicalis)