Interaction of isolated Lp(a) lipoprotein with calcium ions and glycosaminoglycans in vitro

Abstract

The interaction between the lipoprotein carrying the Lp(a) antigen, i.e., the Lp(a) lipoprotein, and agarose gels substituted with glycosaminoglycans, as well as the precipitation of the Lp(a) lipoprotein by Ca2+ were studied. Comparisons between Lp(a) lipoprotein and other serum lipoproteins were conducted. Very low density lipoprotein (VLDL) and low density lipoprotein (LDL) were bound to the tested glycosaminoglycans at a low ionic strength of NaCl, but no binding was found with the Lp(a) lipoprotein. However, Ca2+ as a divalent buffer cation gave a precipitating Ca2+-Lp(a) lipoprotein complex even at a physiological Ca2+ concentration. VLDL and LDL were not precipitated under these conditions. These findings may be of interest in relation to the previously reported higher frequency of the phenotype Lp(a+) in human subjects with coronary heart disease.