The high concentration of Arg213-->Gly extracellular superoxide dismutase (EC-SOD) in plasma is caused by a reduction of both heparin and collagen affinities.
Petersen SV, Olsen DA, Kenney JM, Oury TD, Valnickova Z, Th?gersen IB, Crapo JD, Enghild JJ. The high concentration of Arg213-->Gly extracellular superoxide dismutase (EC-SOD) in plasma is caused by a reduction of both heparin and collagen affinities. Biochem J. 2005 Jan 15; 385(Pt 2):427-32.