Studies of the binding activity to different gonadal receptors of ovine luteinizing hormone (LH) after chemical modification of lysine residues

Abstract

Several LH derivatives obtained by modification of the lysine residues were studied by the radioligand receptor assay using either corpora lutea homogenates or testis homogenates and tritiated methylated LH. The binding activity found was very similar to the biological activity as determined in the ovarian ascorbic acid depletion test, although some minor differences were observed. The binding activity of the methylated derivatives was no different from that of native LH, whereas the other alkylated derivatives were less active or inactive. As expected, carbamylated LH was inactive and the activity of guanidinated LH was considerably reduced. Some differences were observed in the binding affinities of these derivatives when comparing corpora lutea with testicular homogenates.