Variant forms of galanin isolated from porcine brain.

In a peptide concentrate, prepared from acid extracts of porcine brain, several galanin-like immunoreactive peptides were detected and two of these were purified. Characterization of the peptides by sequence analysis, mass spectrometry, and capillary zone electrophoresis identified them as a N-terminally nine residue elongated form of galanin, preprogalanin(24-61) amide, and as an N-terminally four residue truncated form of galanin corresponding to preprogalanin(37-61) amide. The former finding suggests that the removal of the signal peptide in preprogalanin occurs by enzymatic cleavage between glycine-23 and leucine-24. The presence of truncated galanin might refer to a mechanism, where galanin is inactivated by removal of functionally important amino acid residues from the N-terminus.