THE EFFECT OF HEPARIN ON CU2-MEDIATED OXIDATION OF HUMAN LOW-DENSITY LIPOPROTEINS()

The effect of heparin (IIE) on the susceptibility of human low-density lipoprotein (LDL) to Cu2+-induced oxidation was investigated by monit oring conjugated diene formation, HE did not modify the maximum format ion of conjugated diene, but increased markedly the lag phase, The plo t of change in oxidation rate vs. time showed that the absolute value of V-max was dependent on Cu2+ concentration and that HE increased the time necessary to reach V-max. The value of constant K (the Cu2+ conc entration producing a t(lag) of twice the minimum value) increased in the presence of HE, whereas the value of t(min) (the time theoreticall y required for LDL oxidation at an infinite Cu2+ concentration) was no t substantially affected, These results indicate that HE might play a protective antioxidant effect on LDL, probably affecting both the stru ctural properties of the particle and the amount of Cu2+ available for the oxidation.