Polymorphism of human pituitary lutropin (LH). Isolation and partial characterization of seven isohormones.

The complete microheterogeneous system of human pituitary lutropin was demonstrated by gel isoelectric focusing. In addition 7 LH isohormones could be isolated by preparative column focusing and characterized with respect to physicochemical, biological and immunological properties. The in vivo biopotencies ranged from 4.50-11.50 IU/mg, the in vitro bioactivity was from 1.20-10.10 IU/mg, and the immunological activity was from 3.10-7.55 IU/mg. The sialic acid content was found to be 1.8-3.2%. Treatment with neuraminidase resulted in a shift of all bands to the alkaline region, however the 7 LH forms were still present.