Hybrids from equine LH: alpha enhances, beta diminishes activity.

Abstract LH hybrids were prepared by combining eLHα and eLHβ with the corresponding subunits of oLH, pLH and hCG. Recombinants were isolated by gel filtration and assessed by SDS-polyacrylamide gel electrophoresis under both dissociating and non-dissociating conditions. All combinations of subunits produced hybrid LH molecules. Hybrids prepared by combining eLHβ with oLHα, pLHα or hCGα were very inactive in rat radioligand and Leydig cell in vitro bioassays. Hybrids prepared with eLHα were very active in both assays. The greatest potentiating activity was observed when eLHα was combined with pLHβ. The resulting hybrid was 49 times as active as pLH in stimulating steroidogenesis by Leydig cells.