Modified lipid-protein interactions in Tangier beta lipoprotein (LDL2) demonstrated by fluorescence quenching

• Published in: Chemistry and physics of lipids Vol. 49; no. 3; p. 153
• Main Authors: Dumon, M F, Dang, Q Q, Salvayre, R, Clerc, M, Douste-Blazy, L
• Format: Journal Article
• Language: English
• Published: Ireland 01-12-1988
• Subjects: Adult; Apolipoprotein B-100; Apolipoproteins B - blood; Blood Protein Electrophoresis; Cholesterol - blood; Cholesterol Esters - blood; Fluorometry; Humans; Hypolipoproteinemias - blood; Lipoproteins, LDL - blood; Male; Protein Conformation; Tangier Disease - blood; Triglycerides - blood
• ISSN: 0009-3084
• DOI: 10.1016/0009-3084(88)90002-3

Fluorescence quenching by iodide ions has been found to be higher in isolated Tangier low density lipoprotein (LDL2) than in isolated normal LDL2. Apolipoprotein (apo) B-100 is the main protein component of these lipoproteins and its tryptophanyl residues (Trp) are known to be the most hydrophobic and to be responsible for protein fluorescence. Trp exposure can thus be calculated; it was 0.50 in Tangier and 0.42 and 0.41 in insulin-dependent diabetics (IDD) and normal controls, respectively. The greater fluorescence quenching of Tangier LDL2 reveals a shallower embedding of Trp which is principally due to a lowered free cholesterol (FC) level in the shell and a smaller lipid core, itself dependent on a drop in cholesterol esters (CE). This is in accordance with the electrophoretic properties of Tangier LDL2 and suggests that Tangier LDL2 may be considered to be modified.