Dependence on heparin chain-length of the interaction of heparin with human plasma low density lipoproteins.

Successive rechromatography of commercial bovine lung heparin on human plasma low density lipoproteins (LDL) immobilized to AffiGel-10 yielded four high reactive heparin (HRH-I to IV) fractions and an unreactive fraction (URH). HRH-I was the most sulphated HRH fraction whereas URH had the least sulphation. In the presence of 10 mM Ca2+, LDL were precipitated by these heparins in the following order: HRH-II greater than HRH-III greater than HRH-IV greater than HRH-I greater than URH. The average molecular weight of HRH-I to IV was 8600, 11400, 10,100, and 10,000, respectively. A plot of log molecular weight versus the concentration of HRH required to give half-maximal precipitation of LDL showed a negative correlation (r = -0.880). These results indicate that heparin chain length is an important determinant of heparin binding to LDL in solution and may have relevance to the binding and precipitation of LDL in the arterial wall.