Hemocyanin of the molluscan Concholepas concholepas exhibits an unusual heterodecameric array of subunits

Pablo De Ioannes, Bruno Moltedo, Harold Oliva, Rodrigo Pacheco, Fernando Faunes, Alfredo E. De Ioannes, María Inés Becker

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47 Citations (Scopus)


We describe here the structure of the hemocyanin from the Chilean gastropod Concholepas concholepas (CCH), emphasizing some attributes that make it interesting among molluscan hemocyanins. CCH exhibits a predominant didecameric structure as revealed by electron microscopy and a size of 8 MDA by gel filtration, and, in contrast with other mollusc hemocyanins, its stabilization does not require additional Ca2+ and/or Mg2+ in the medium. Polyacrylamide gel electrophoresis studies, analyses by a MonoQ FPLC column, and Western blots with specific monoclonal antibodies showed that CCH is made by two subunits nonco-valently linked, named CCH-A and CCB-B, with molecular masses of 405 and 350 kDa, respectively. Interestingly, one of the subunits undergoes changes within the macromolecule; we demonstrated that CCH-A has an autocleavage site that under reducing conditions is cleaved to yield two polypeptides, CCH-A1 (300 kDa) and CCH-A2 (108 kDa), whereas CCH-B remains unchanged. The CCH-A nick occurs at 4 °C, increases at 37 °C, and is not inhibited by the addition of protease inhibitors and/or divalent cations. Since the CCH structure is a heterodimer, we investigated whether subunits would be either intermingled, forming heterodecamers, or assembled as two homogeneous decamers. Light scattering and electron microscope studies of the in vitro reassociation of purified CCH subunits demonstrated that the sole addition of Mg2+ is needed for its reassembly into the native decameric molecule; no homodecamer reorganization was found with either CCH-A or CCH-B subunits alone. Our evidence showed that C. concholepas hemocyanin is an unusual example of heterodecameric organization.

Original languageEnglish
Pages (from-to)26134-26142
Number of pages9
JournalJournal of Biological Chemistry
Issue number25
Publication statusPublished - 18 Jun 2004

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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