J. Biochem, 1988, Vol. 104, No. 1 62-65
© 1988 Japanese Biochemical Society
research-article |
Circular Dichroism Study of Membrane Dynamics Focused on Effect of Monosialogangliosides1
*Artificial Cells & Organs Research Centre, McGill University 3655 Drummond Street, Montreal, PQ, Canada H3G 1 Y6
**Department of Synthetic Chemistry, Kyoto University Sakyo-ku, Kyoto, Kyoto 606
Monosialogangliosides (GM) purified from bovine brain were incorporated into circular dichroism (CD)-active liposomes and the effects of GMM on the membrane dynamics were studied by CD spectroscopy. In the presence of 7 mol% of GMM, the phase transition temperature (Tc) of the membrane increased by ca. 10 compared with the membrane without GMM and characteristic CD spectra were observed for CD-active liposomes incorporating GM at low temperature. Asialogangliosides had no effect on the CD spectra or Tc. We have also studied the role of GMM in reducing leakage of [3H] sucrose from liposomes composed of egg phosphatidyicholine, dipalmitoyl phosphatidic acid, cholesterol and a-tocopherol with a molar ratio of 4: 1 : 5: 0.1 in the presence of human plasma at 25 The half-life of [3H]-sucrose leakage was 173 h for liposomes incorporating 7 mol% of GMM. On the other hand, the half-lives for liposomes incorporating 7 mol% of asialogangliosides and liposomes without glycolipids were 45 and 42 h, respectively. These results indicate that sialic acid on the membrane surface contributes to the increase of Tc, to the change of the aggregation state of phospholipids and to the stabilization of liposomes in plasma.
1 These studies were made possible by a grant from the Ministry of Higher Education, Science and Technology of Quebec.