title: Heterogeneity of human luteinizing hormone. Discrimination between acidic and basic preparations.
abstract: The charge heterogeneity of an I. H preparation containing relatively acidic components (LH Type 1) was studied. Four biological active components, with pI-values of 5.04, 5.60, 6.06 and 6.57 were detected. A total of four different alpha-subunits, with pI-values of 4.49, 4.79, 5.16 and 6.02 could be detected after incubation at 37 degrees C. With the exception of the most acidic component all these alpha-subunits were also present in earlier studied 1.H Type II preparations. After neuraminidase treatment a strong shift to more basic components was observed, resulting in a population of components similar to the one detected in I.H Type II preparations. The beta-subunits detected were very different from those observed in Type II preparations. All six components detected had pI-values greater than 7.5. Upon incubation at 56 degrees C these subunits appeared to be unstable resulting in a shift to more basic pI-values these pI-values being very similar to those of beta-subunits observed before in Type II preparations. After neuraminidase treatment, the pH values of the population of beta-subunits became identical to those of the population in I.H Type II. From these results it is concluded that the major charge difference between LH Type I and Type II is located in the beta-subunits. This difference cannot be explained completely by differences in sialic acid content, but may also be due to heat labile charged groups such as sulphate.
authors.affiliation: National Institute of Public Health and Environmental Protection, Bilthoven, The Netherlands.
authors.forename: L A
authors.initials: LA
authors.lastname: van Ginkel
authors.forename: J G
authors.initials: JG
authors.lastname: Loeber
mesh_terms: D001681:Biological Assay; D002850:Chromatography, Gel; D006801:Humans; D066298:In Vitro Techniques; D007525:Isoelectric Focusing; D007986:Luteinizing Hormone / Q000032:analysis*; D008968:Molecular Conformation; D009439:Neuraminidase / Q000494:pharmacology; D011863:Radioimmunoassay; D012794:Sialic Acids / Q000032:analysis
chemical_list: D012794:Sialic Acids; D007986:Luteinizing Hormone; D009439:Neuraminidase