Lipoprotein-elastin interactions in human aorta fibrous plaque lesions

The nature of lipoprotein and elastin associated with hyaluronate in human atherosclerotic plaque tissue was studied by digesting the tissues with elastase. The elastase-solubilized lipoprotein-hyaluronate complexes, isolated by Bio-Gel A-50m column chromatography, contained 7.8 mg calcium/100 mg protein. The Sephadex G-200 chromatography of delipidated complexes yielded high (fraction I) and low (fraction II) molecular weight protein fractions. Dialysis of the complexes against 0.01% EDTA resulted in removal of fraction II. Fraction I reacted immunologically against antihuman LDL, and its amino acid composition resembled that of human apoB. Fraction II contained 5 peptide fragment and had high levels of nonpolar amino acids that are characteristic of elastin. However, these peptides also contained high levels of polar amino acids, thus resembling the plaque elastin. These findings suggest that certain regions of plaque elastin may have affinity for apoB containing lipoproteins and calcium.