Immunohistochemical analysis of the cross-reaction of anti-rat histidine decarboxylase antibody with guinea-pig DOPA decarboxylase

Abstract

L-Histidine decarboxylase [L-histidine carboxylyase, HDC, EC 4.1.1.22] is an enzyme distinct from L-DOPA decarboxylase [L-aromatic amino acid carboxylyase, DDC, EC 4.1.1.28]: the two decarboxylases from fetal rat liver were completely separated from each other by DEAE-cellulose column chromatography and by affinity chromatography with L-carnosine as a ligand. The antibody raised against this HDC inhibited the HDC's from rat and guinea-pig brains very strongly, but their DDCs very weakly. However, in immunofluorescent histochemical studies, the antibody cross-reacted with DDC-like immunoreactive structures, such as chromaffin cells of the adrenal medulla, the raphe nucleus, the substantia nigra, and the locus coeruleus of the brain of guinea-pigs, but not of rats, suggesting that these two decarboxylases share some antigenic structures.