PURIFICATION AND PARTIAL CHARACTERIZATION OF ISOFORMS OF LUTEINIZING-HORMONE FROM THE CHICKEN PITUITARY-GLAND

Isoforms of chicken luteinizing hormone (cLH) were isolated from chick en pituitaries by differential extraction, sequential chromatography o n HPLC cation- and anion-exchange columns, and gel-filtration chromato graphy. Three purified isoforms of the cLH had high biological potency in the chicken granulosa cell LH bioassay (4.21-7.4 x NIH-LH-S1 U/mg) . One cLH isoform without detectable biological activity showed substa ntial immunological activity in a homologous cLH radioimmunoassay. The cLH isoforms contained negligible follicle-stimulating hormone activi ty, but some contained thyroid-stimulating hormone activity. The appar ent molecular weight of cLH was 37,000 Da, and the holoprotein consist ed of subunits with a molecular weight of approximately 17,000 Da.