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Adsorption of thionine on heparin studied by combining ultrafiltration and difference VIS spectroscopy
Author(s) -
Nothelfer R.,
Ruprecht J.,
Baumgärtel H.
Publication year - 1986
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360250708
Subject(s) - thionine , chemistry , binding constant , ultrafiltration (renal) , enthalpy , titration , spectroscopy , analytical chemistry (journal) , inorganic chemistry , binding site , chromatography , thermodynamics , electrochemistry , biochemistry , physics , electrode , quantum mechanics
The combination of ultrafiltration and difference spectroscopy allows the quantitative determination of spectra of thionine bound to heparin. The spectra of the bound dye do not depend on the degree of coverage; this and the shape of the Scatchard plot show that “all‐or‐none” binding is valid. A calculus of variations based on a modification of the Hill plot shows that aggregates of seven thionine cations are bound. Tetrasaccharides with an average charge of two carboxylate and five sulfate groups are suggested to be the binding sites. The binding constant given for one mole thionine is 4.4 · 10 5 M −1 . The Gibbs enthalpy for binding of one mole of thionine is −31.7 kJ·M −1 at 20°C.