Isolation and characterization of the subunits of porcine follicle-stimulating hormone.

The alpha and beta subunits of porcine FSH were isolated and purified to homogeneity as judged by SDS disc gel electrophoresis. The isolated subunits had less than 1% of the biological activity of the native hormone but were capable of recombining to generate at least 23% of the activity of the native hormone. The molecular weights calculated from hydrodynamic properties were 12,600 for pFSH alpha and 17,200 for pFSH beta. Total carbohydrate (g/100 g) was 18.9 for alpha and 15.1 for beta. The sialic acid content of alpha (3.8 g/100 g) exceeded that of beta (0.2 g/100 g). The alpha subunit contained significantly more lysine, alanine phenylalanine and methionine and significantly less aspartic acid, threonine, valine, isoleucine, leucine and tryptophan than the beta subunit. Evidence was found for N-terminal heterogeneity and an internal cleavage in the isolated alpha subunit.