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Viscosity at low shear and circular dichroism studies of heparin
Author(s) -
Chung M. Ching Ming,
Ellerton Nerida F.
Publication year - 1976
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.1976.360150713
Subject(s) - chemistry , circular dichroism , heparin , divalent , ionic strength , viscosity , crystallography , inorganic chemistry , organic chemistry , thermodynamics , aqueous solution , biochemistry , physics
The viscosity of heparin solution was investigated under conditions of low shear stress between 0.0193 and 0.222 dyne cm −2 , in water, in the presence of various cations (Na + , K + , Cs + , Mg 2+ , Ba 2+ , Cu 2+ ) and at several pH's. The viscosity was found to decrease with in creasing shear stress. Shear dependence was greatest in the absence of added salts, and decreased as the ionic strength increased. Differences in viscosity in the presence of various cations appear to be related to the binding affinity of these cations to heparin. Viscosity studies of the periodate oxidation of heparin confirmed that heparin contains vicinal hydroxyl groups in its primary structure. Circular dichroism spectra of the same heparin solutions were also studied. The binding process between Cu 2+ and heparin appears to be different from that of other divalent ions. A reduction in the pitch of the helix would qualitatively explain the conformational changes that occur on binding Cu 2+ to heparin. These changes are reversible on removal of Cu 2+ and replacement with Na + . The circular dichroism spectrum was virtually lost for periodateoxidized heparin.