Abstract
The interaction of isolated Lp(a) lipoprotein or other lipoprotein classes with different glycosaminoglycans (GAG) bound to activated Sepharose was studied. [Apparently this binding mechanism is important in lipid accumulation in atherosclerotic lesions in humans.] In contrast to LDL [low density lipoprotein], the Lp(a) lipoprotein did not bind to the GAG tested if Na+ was used as a buffer cation, but in the presence of Ca2+ even the Lp(a) lipoprotein was bound to GAG. This type of binding, probably mediated by divalent cation bridges, is apparently not a simple function of the GAG used. Addition of GAG in solution revealed that this binding, and the binding in the absence of Ca2+, is reversible. The Ca2+ mediated binding may be the only one existing under physiological conditions, and it appears possible that the Lp(a) lipoprotein is bound more firmly to GAG than is LDL under such conditions.