The increase in FSH receptor-binding activity of equine gonadotropin subunit hybrids following PNGase digestion in the analytical-scale experiments was a combination of both increased dimer formation resulting from removal of a steric barrier to dimerization and increased receptor-binding affinity resulting from elimination of a direct inhibitory effect of Asn56 oligosaccharide on receptor binding.
The latter effect was demonstrated in experiments involving purified eFSHp hybrid preparations and purified eLHpt hybrid preparations, because there were no unassociated subunits in these preparations. A similar pattern of increasing receptor-binding inhibition was associated with increasing length of the Man(al-6)Man oligosaccharide branch (eCGa > eFSHa > eLHa). All of these differences in receptor-binding activity were larger and were statistically significant for eLHpt hybrid preparations but were reduced in magnitude for the eFSHp hybrid preparations such that only the largest difference between eLHa:eFSHp and eCGa:eFSHp was consistently a significant difference. buy levaquin online