TY - JOUR
T1 - Effect of phase transition on the distribution of membrane-associated particles in microsomes
AU - Duppel, Wilfried
AU - Dahl, Gerhard
N1 - Funding Information:
The authors are indebted to Professor V. Ullrich and Dr. M. Gratzl for helpful discussions. We gratefully acknowledge the excellent technical assistance of Mr. U. Br6gmann, Mrs. I. Kiimmel and Mr. R. Weiss. This work was supported by the Sonderforschungsbereich 38 (Membranforschung) of the Deutsche Forschungs-gemeinschaft.
PY - 1976/3/19
Y1 - 1976/3/19
N2 - 1. 1 Rat liver microsomes were studied by freeze-fracture electron microscopy. The distribution of membrane-associated particles indicated the right-side-out orientation of microsomal vesicles. Studies at different temperatures were performed. At 30°C membrane-associated particles are randomly distributed on membrane A-faces, while aggregations of particles are observed at 4°C. 2. 2 Aggregation is dependent on the cooling rates. It can be prevented by shock-freezing. 3. 3 Particle aggregation is also prevented by cholesterol, added to the microsomes in equal molar ratio to the microsomal phospholipid content. 4. 4 These findings suggest that particle aggregation is caused by a partial freezing-out of phospholipid molecules during the phase transition from the liquid-crystalline to the gel state. 5. 5 The results are discussed with respect to an observed increase in activation energy of microsomal drug monooxygenation at lower temperature.
AB - 1. 1 Rat liver microsomes were studied by freeze-fracture electron microscopy. The distribution of membrane-associated particles indicated the right-side-out orientation of microsomal vesicles. Studies at different temperatures were performed. At 30°C membrane-associated particles are randomly distributed on membrane A-faces, while aggregations of particles are observed at 4°C. 2. 2 Aggregation is dependent on the cooling rates. It can be prevented by shock-freezing. 3. 3 Particle aggregation is also prevented by cholesterol, added to the microsomes in equal molar ratio to the microsomal phospholipid content. 4. 4 These findings suggest that particle aggregation is caused by a partial freezing-out of phospholipid molecules during the phase transition from the liquid-crystalline to the gel state. 5. 5 The results are discussed with respect to an observed increase in activation energy of microsomal drug monooxygenation at lower temperature.
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U2 - 10.1016/0005-2736(76)90386-2
DO - 10.1016/0005-2736(76)90386-2
M3 - Article
C2 - 1268205
AN - SCOPUS:0017237490
VL - 426
SP - 408
EP - 417
JO - Biochimica et Biophysica Acta - Biomembranes
JF - Biochimica et Biophysica Acta - Biomembranes
SN - 0005-2736
IS - 3
ER -