PubMed1985
The immunoreactive growth hormone composition of a pituitary extract has been compared by conventional gel filtration chromatography (pH 8), and reversed-phase high-performance liquid chromatography (pH 2) on a wide-pore (300 A) short-chain column. By gel filtration chromatography, four peaks of immunoreactivity were obtained, labelled "monomer", "dimer", "aggregate" and "void". However, by high-performance liquid chromatography all of these fractions were themselves shown to be multicomponent mixtures. The "monomer" peak contained at least two forms (M1 and M2). The "dimer" fraction contained three peaks, two of which co-eluted with M1 and M2, and a third component, D. Similarly, the aggregate fraction contained M1, M2, D and a fourth component, A. The "void", in contrast, contained mostly M1 and M2 with very little D. One interpretation of these results is that M1 (the 22K molecular weight monomeric form) and M2 (a chemically modified form of M1) are present in all molecular weight fractions in loosely bound aggregates which break up under acidic conditions. D and A are probably oligomeric forms of growth hormone (possibly a dimer and higher molecular weight species, respectively).