Studies of the heterogeneity of human pituitary LH by fast protein liquid chromatography

Abstract

The Pharmacia fast protein liquid chromatography system was employed to fractionate a purified preparation of human LH (hLH) on the anion exchanger Mono Q at pH 7·8 into 14 sub-fractions. Each of the sub-fractions was characterized by its behaviour on polyacrylamide gel electrophoresis, sodium dodecyl sulphate (SDS) gel electrophoresis, LH receptor binding activity and sialic acid content. All sub-fractions contained sialic acid, were active in binding to LH receptors, and exhibited components typical of hLH subunits on SDS gel electrophoresis. None of the sub-fractions was homogeneous with respect to charge. There is evidence that part of the heterogeneity results from the presence in some molecules of an internal proteolytic cleavage within the β-subunit, and fractions enriched in species containing such cleavages were prepared by this method. J. Endocr. (1985) 105,405–413