Metal ion coordination of macromolecular bioligands: Formation of zinc(II) complex of hyaluronic acid

Kálmán Burger, János Illés, Béla Gyurcsik, Mária Gazdag, Erika Forrai, Imre Dékány, Katalin Mihályfi

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24 Citations (Scopus)

Abstract

The coordination of zinc(II) ion to hyaluronate (Hya), a natural copolymer, in aqueous solution at pH 6 was investigated by potentiometric and circular dichroism (CD) spectroscopic methods, and by monitoring the changes in macroscopic properties by high-precision measurements. The zinc(II)-selective electrode, and CD measurements proved the binding of zinc(II) by Hya. A number of Hya fragments (Mr ∼ 3.3 × 103-1.4 × 106) were studied to estimate the contributions of the polyelectrolyte effect, the solvation and host-guest interactions to the extra stabilization of the macromolecular zinc(II) complexes as compared with the monomeric unit. The zinc(II) ion activity increase reflected a stability decrease for the fragments with Mr < 4 × 104. This molecular weight differs from that where cleavage of the Hya skeleton starts (∼5 × 105, according to the size-exclusion gel, and anion-exchange chromatographic behavior of the Hya fragments) and from that where the polyelectrolyte effect stops (∼6 × 103). The excess volumes and Bingham shear yield values of the solutions revealed the transformation of the coherent random coil structure stabilized by intermolecular association in the NaHya to an intramolecular association producing the globular structure of the ZnHya molecule, with a smaller but more strongly bound solvate water sheet.

Original languageEnglish
Pages (from-to)197-207
Number of pages11
JournalCarbohydrate Research
Volume332
Issue number2
DOIs
Publication statusPublished - May 18 2001

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Keywords

  • Anion exchange
  • Extra stabilization
  • Hyaluronic acid fragments
  • Size-exclusion gel chromatography
  • Zinc(II)-hyaluronate complex
  • Zn-selective electrode

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Organic Chemistry

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