Heparin, negatively charged

The numerous negative charges are significant in several respects (1) they contribute to the poor membrane penetrability—heparin is ineffective when applied by the oral route or topically onto the skin and must be injected (2) attraction to positively charged lysine residues is involved in complex formation with ATIII (3) they permit binding of heparin to its antidote, protamine (polycationic protein from salmon sperm). 

T14. Heparin Interactions Heparin, a highly negatively charged glycosaminoglycan, is used clinically as an anticoagulant. It acts by binding several plasma proteins,... 

The heparin-sensitive electrode at the beginning of this chapter is similar to the Ca2+ electrode, but the ion exchanger in the membrane is tridodecylmethylammonium chloride, (C,2H25)3NCH C1- Cl in the membrane exchanges with the negatively charged heparin. 

The ideal surface for contact with human blood is the surface of blood vessels, and the immediate surface contains heparinoid complexes. Heparin, a negatively charged polysaccharide, has been bonded to silicon rubber and other polymers. In one procedure, a quaternary ammonium compound is first adsorbed on die polymer substrate and heparin is 111 turn adsorbed on the positively charged surface. Chemical bonding of heparin has also been achieved. Such surfaces do not cause clotting of contacted blood. 

All the synthesized HC copolymers were negatively charged, as only the part of the negatively charged groups of the heparin macromolecule is involved in the reaction with the quaternized ammonium groups, while the other remain unneutralized. 

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