[Effect of sterols on melittin incorporation into liposomal membranes].
Effects of various sterols on the values of intensity, spectrum position and polarization of tryptophan fluorescence (P) of melittin incorporated in lecithin liposomes at different lipid/protein molar ratios (Ri) were studied. A difference in sterol effects has been revealed at the values of Ri > 5. At Ri < 5, fluorescence parameters were determined mainly by melittin in the aqueous solution. Assuming that melittin was bound to lecithin, the lecithin/melittin binding ratio was found to be in the range of 25-50. Unlike cholesterol and stigmasterol, the incorporation into membranes of ergosterol and 7-dehydrocholesterol produced a decrease in the intensity of tryptophan fluorescence and an increase in the P value. This difference might result from the presence of an additional double bond in one of sterol rings of ergosterol and 7-dehydrocholesterol molecules. Analysis of the results obtained enabled us to suggest that the structure of the steroid B ring is responsible for the effect exerted by sterols on melittin-lipid interactions.
Adamian
S Ia
SIa
Institute of Cytology, Russian Academy of Sciences, St. Petersburg.
Kaulin
Iu A
IuA
Kuznetsova
I M
IM
Turoverov
K K
KK
Shchagina
L V
LV
D005454:Fluorescence Polarization; D008081:Liposomes; D008555:Melitten / Q000737:chemistry*; D008567:Membranes, Artificial; D015394:Molecular Structure; D010713:Phosphatidylcholines / Q000737:chemistry; D013261:Sterols / Q000737:chemistry*
D008081:Liposomes; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D013261:Sterols; D008555:Melitten
Vliianie sterinov na vstraivanie melittina v liposomal'nye membrany.