Abstract
CHOLESTEROL is a major constituent of the phospholipid bilayer of many biological membranes. The ratio of cholesterol to phospholipid seems to be an important determinant of the physical and biological properties of membranes1. Although several model systems now provide a molecular basis for understanding preferential interaction of cholesterol with different phospholipids2,3, the distribution and location of cholesterol in lipid bilayers has not been clearly established. A recent study4 demonstrated marked differential susceptibility to oxidation by cholesterol oxidase (EC 1.1.3.6) of cholesterol in the inner and outer layers of the erythrocyte membrane. Another series of experiments revealed that cholesterol in a virus membrane was accessible to oxidation by cholesterol oxidase only when external phospholipid headgroups were removed by phospholipase C (ref. 5). We report here our studies on the usefulness of the enzymatic action of cholesterol oxidase to probe the membrane bilayer distribution of cholesterol and its differential interaction with choline-containing and amino-containing phospholipids. To this end, enzymatic oxidation of cholesterol was measured in mixed lipid vesicles composed of various phospholipids and cholesterol. The possible application of this technique to biological membranes was also investigated using the membranes of human erythrocytes and vesicular stomatitis (VS) virus.
Original language | English |
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Pages (from-to) | 394-395 |
Number of pages | 2 |
Journal | Nature |
Volume | 274 |
Issue number | 5669 |
DOIs | |
State | Published - 1978 |