title: Quantitative variations of the isoforms in haptoglobin 1-2 and 2-2 individual phenotypes.
abstract: Haptoglobin is a hemoglobin-binding protein presenting in humans three distinct phenotypes (Hpt 1-1, Hpt 1-2, or Hpt 2-2). The Hpt 1-2 and Hpt 2-2 phenotypes are in turn represented by populations of isoforms. The relative amounts of the major isoforms of Hpt 1-2 and Hpt 2-2 were found to differ not only in different individuals, but also in the same individual before and after a physical effort. Exercise-dependent changes in the plasma concentrations of ascorbate, urate, alpha-tocopherol, retinol, and glutathione were also observed, but correlations between such changes and those of the amount for any isoform were not found. Samples of Hpt 1-2 or Hpt 2-2 were challenged with oxidants (H(2)O(2) with ferrous ions, spermine-NO, KO(2), and 3-morpholinosydnonimine), but the isoform levels were not altered. Hpt 2-2 isoforms were present in Hpt 1-2, as minor species. Furthermore, different isoforms exhibited different hemoglobin binding abilities. Thus, these parameters should also be taken into consideration in studies correlating Hpt phenotypes prevalence with pathologies or functional differences.
authors.affiliation: Dipartimento di Fisiologia Generale ed Ambientale, Università di Napoli Federico II, via Mezzocannone 8, Naples 80134, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Cigliano
authors.forename: Maria Stefania
authors.initials: MS
authors.lastname: Spagnuolo
authors.forename: Paolo
authors.initials: P
authors.lastname: Abrescia
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D014644:Genetic Variation; D006242:Haptoglobins / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000502:physiology*; D006454:Hemoglobins / Q000737:chemistry; D006801:Humans; D008297:Male; D008970:Molecular Weight; D010641:Phenotype; D011485:Protein Binding; D011487:Protein Conformation; D020033:Protein Isoforms / Q000097:blood / Q000737:chemistry / Q000145:classification / Q000502:physiology
chemical_list: D000975:Antioxidants; D006242:Haptoglobins; D006454:Hemoglobins; D020033:Protein Isoforms