MOLECULAR-MASS AND ISOELECTRIC PROPERTIES OF PITUITARY AND URINARY GONADOTROPINS IN CALLITRICHID PRIMATES

In this study, the molecular masses and isoelectric characteristics of pituitary LH and FSH in two species of callitrichid primate, the comm on marmoset (Callithrix jacchus) and the cotton-top tamarin (Saguinus oedipus), were determined. Comparative data for urine samples from Cal lithrix jacchus are also presented. The separation of gonadotrophins f rom pituitary extracts and urine was performed under nonreducing condi tions using SDS-PAGE and isoelectric focusing procedures. Hormone acti vity in gel eluates was determined by in vitro bioassays for LH and FS H and by a microtitre plate enzymeimmunoassay for LH. The molecular ma sses of pituitary and urinary proteins were between 36 and 37 kDa for LH and FSH, and were similar in both species. A dimer form of pituitar y LH with a molecular mass of 33 kDa was also found in the cotton-top tamarin, but not in the marmoset. Guanidine-HCl dissociation of gonado trophins from marmoset and tamarin pituitaries before electrophoresis gave proteins of 16 and 28 kDa, and 16 and 25 kDa range, respectively. Isoelectric focusing revealed numerous peaks of bioactivity for both LH and FSH, indicating the presence of multiple molecular variants (is oforms) of each hormone. In both species pituitary FSH eluted over a n arrower and more acidic pH range than LH. Isoelectric focusing profile s for pituitary and urinary LH in the marmoset were similar (pH range 5.0-8.5), whereas urinary FSH demonstrated a more acidic profile than the pituitary protein. These results give comparative information on t he properties of New World primate gonadotrophins, which should be use ful in studies of their physiological action and in aiding the develop ment of improved reagents and assays for their detection.