ABSTRACT
This chapter describes how cartridges packed with weak ion-exchangers can be used, in a batch procedure, to fractionate pituitary peptides extracted from bovine posterior pituitaries into basic, acidic, and neutral pools. The ion-exchange fractionation technique is complementary to the C18 Sep-Pak extraction procedure. The Sep-Pak eluates were combined, divided into ten equal portions, and taken to dryness. The cation-exchange eluate was designated the basic pool, while the anion-exchange eluate was designated the acidic pool. The neutral pool contained a single peak of oxytocin accounting for about 50% of that found in the whole tissue extract. The almost complete distribution of peaks into the acidic and basic pools can be rationalized in terms of the charge distributions within the peptide hormone precursors. In contrast, all the acidic peptides, whether weakly charged or not, remained in the acidic pool. This behavior can be correlated well with the relative strengths of the ion-exchangers.
