DO SUBUNITS OF LUTEINIZING HORMONE POSSESS ANY BIOLOGICAL ACIIVITY?

PRAKONG CHOBSIENG

Summary: Antisera raised against subunits of ovine luteinizing hormone (LH) were used to purify subunit preparations and then purified subunits were used to determine whether they possess any inherent biological activity. Reference preparations of ovine LH (NIH-LH-S18, 1 g/ml), -subunit of LH (21 g/ml) or -subunit of IH (23 g/ml) were shown to stimulate cyclic AMP accumulation in immature rat ovaries in vitro. This action of the reference -subunit preparation was completely abolished after absorption of any contamination of -LH subunit as well as intact LH present in the preparation by treatment with an antiserum to the -subunit of purified ovine LH (anti--LH). No change in its immunological properties were observed after the absorption. Similar results were obtained with the reference -subunit preparation, which was not active in stimulation of cyclic AMP accumulation after its absorption with anti--LH but still retained immunological properties. Thus none of the subunits of oville LH has inherent biological activity. The activities of these subunits which were reported in the literature are probably due to the contamination of the subunit preparations by the intact hormone.

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Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand

Received 7 February 1977