Journal of Lipid Research, Vol. 41, 933-939, June 2000
Copyright © 2000 by Lipid Research, Inc.
-Cyclodextrin extracts diacylglycerol from insect high density lipoproteins
Zeina E. Jounia,
Jorge Zamoraa,
Marcus Snydera,
William R. Montforta,
Andrzej Weichsela, and
Michael A. Wellsa
a Department of Biochemistry and Center for Insect Science, Biological Sciences West, University of Arizona, Tucson, AZ 85721
Correspondence to:
Zeina E. Jouni
-Cyclodextrins are water-soluble cyclic hexamers of glucose units with hydrophobic cavities capable of solubilizing lipophiles. Incubating
-cyclodextrin with high density lipophorin from Manduca sexta or Bombyx mori resulted in a cloudy, turbid solution. Centrifugation separated a pale yellowish precipitate. Thin-layer chromatography analysis of the lipid extract of the precipitate showed that the major lipid was diacylglycerol, while KBr density gradient analysis of the supernatant demonstrated the presence of a lipid-depleted very high density lipophorin. Transfer of diacylglycerol from lipophorin to cyclodextrin was specific to
-cyclodextrin and was not observed with ß- or
-cyclodextrins. pH had no effect on diacylglycerol transfer to
-cyclodextrin. However, the transfer was strongly dependent on the concentration of
-cyclodextrin and temperature. Increasing the concentration of
-cyclodextrin in the incubation mixture was associated with the formation of increasingly higher density lipophorins. Thus, at 20, 30, and 40 mM
-cyclodextrin, the density of B. mori lipophorin increased from 1.107 g/ml to 1.123, 1.148, and 1.181 g/ml, respectively. At concentrations greater than 40 mM,
-cyclodextrin had no further effect on the density of lipophorin.
-Cyclodextrin removed at most 83;87% of the diacylglycerol present in lipophorin. Temperature played an important role in altering the amount of diacylglycerols transferred to
-cyclodextrin. At 30 mM
-cyclodextrin, the amount of diacylglycerol transferred at different temperatures was 50% at 4°C, 41% at 15°C, 20% at 28°C, and less than 3% at 37°C.
We propose that diacylglycerol transfers to
-cyclodextrin via an aqueous diffusion pathway and that the driving force for the transfer is the formation of an insoluble
-cyclodextrindiacylglycerol complex.Jouni, Z. E., J. Zamora, M. Snyder, W. R. Montfort, A. Weichsel, and M. A. Wells.
-Cyclodextrin extracts diacylglycerol from insect high density lipoproteins. J. Lipid Res. 2000. 41: 933;939.
Supplementary key words:
lipophorin, fluid-phase transfer, Manduca sexta, Bombyx mori