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Divalent cation interactions with a carboxylated derivative of scleroglucan
Author(s) -
Bosco Marco,
Sussich Fabiana,
Gamini Amelia,
Reisenhofer Edoardo,
Adami Giampiero,
Rizzo Roberto
Publication year - 1995
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1995.021961209
Subject(s) - chemistry , isothermal microcalorimetry , cooperativity , divalent , cooperative binding , carboxylate , circular dichroism , macromolecule , conformational change , crystallography , isothermal titration calorimetry , polymer chemistry , derivative (finance) , stereochemistry , binding site , organic chemistry , biochemistry , thermodynamics , physics , financial economics , economics , enthalpy
Divalent cation binding was investigated on a semisynthetic carboxylate derivative obtained from the fungal polysaccharide scleroglucan. Polarography, circular dichroism and isothermal microcalorimetry were used to study both the binding ability of Cu(II), Pb(II), and Zn(II) ions and the macromolecular properties of the systems under investigation. A theoretical model, proposed by Schwarz for the cooperative binding, was used to evaluate binding constants and the parameter σ related to the degree of cooperativity. All findings are discussed in terms of the differences in the binding ability of the different cations investigated. Pb(II) ions exhibit the higher affinity for oxidised scleroglucan and, in addition to this, its binding process is characterised by a cooperative behavior due to the onset of a disorder‐to‐order conformational transition of the polysaccharidic backbone. On the other hand, Cu(II) ions are less effective in the binding and unable to induce the conformational transition.