ASSOCIATION OF LUTEINIZING HORMONE ACTIVITY WITH AN ACIDIC PROTEIN FROM SHEEP PITUITARY GLANDS

Abstract

A fraction possessing luteinizing hormone activity isolated by chromatography on a carboxymethyl cellulose ion exchange column and previously designated LH1 has been studied. The potency of this fraction relative to a reference standard was less when assayed by the ovarian ascorbic acid depletion method than previously obtained with the ventral prostate assay in hypophysectomized rats. It has been found that the LH1 fraction possesses heterogeneity upon sedimentation in the ultracentrifuge directly after chromatography, thus does not dissociate into other molecules with luteinizing activity with subsequent handling as previous evidence had suggested. The LH1 fraction was shown to arise from association of luteinizing activity with an acidic "combining" protein from the original sheep pituitary glands. Thus the LH1 fraction was a chromatographic artefact and presumably has no physiological significance. The "combining" protein was analyzed for its amino acid composition to demonstrate the acidic nature of this material.