Oxygenated cholesterols synergistically immobilize acyl chains and enhance protein helical structure in human erythrocyte membranes.
Fourier transform infrared spectroscopy revealed that insertion of 20 alpha-hydroxycholesterol into human erythrocyte membranes (10% of total membrane sterol) immobilized the lipid acyl chains to a degree equivalent to enriching total membrane cholesterol by 50% (Rooney, M.W., Lange, Y. and Kauffman, J.W. (1984) J. Biol. Chem. 259, 8281-8285). Raman spectroscopy showed that the amount of acyl chain rotamers was not significantly altered by the presence of 20 alpha-hydroxycholesterol, indicating that acyl chain immobilization was limited to an inhibition of lateral motion. The presence of 20 alpha-hydroxycholesterol may synergistically enhance the acyl-chain-immobilizing behavior of membrane cholesterol. In addition, protein helical structure was not altered by 20 alpha-hydroxycholesterol. The insertion of 7 alpha-hydroxycholesterol into erythrocyte membranes resulted in an increase in protein helical structure which was comparable to that observed for erythrocyte membranes enriched with pure cholesterol by 50%. However, both acyl chain mobility and conformation were unchanged. These results suggest a synergistic behavior between oxysterols and cholesterol in modifying erythrocyte membrane packing.
D002784:Cholesterol / Q000097:blood*; D004910:Erythrocyte Membrane / Q000502:physiology*; D006801:Humans; D006888:Hydroxycholesterols / Q000097:blood*; D008051:Lipid Bilayers / Q000097:blood; D008560:Membrane Fluidity; D008565:Membrane Proteins / Q000097:blood*; D011487:Protein Conformation
D006888:Hydroxycholesterols; D008051:Lipid Bilayers; D008565:Membrane Proteins; C025813:20-hydroxycholesterol; C011724:cholest-5-en-3 beta,7 alpha-diol; D002784:Cholesterol