Effects of maleylation on the lipid-binding and immunochemical properties of human plasma high density apolipoprotein-A-II

Chemical modification by maleylation of the human plasma high density lipoprotein-protein, apoA-II, causes significant changes in its properties. These changes are as follows: 1) a shift from a helical to a more disordered secondary structure; 2) a decreased ability to bind egg phosphatidylcholine vesicles; and 3) a decrease in immunoreactivity as measured by a quantitative radioimmunoassay. Each of these changes was reversed by demaleylation. These results are discussed in relation to a molecular theory of lipid binding by the plasma lipoproteins.