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Transbilayer Phosphatidylcholine Distributions in Small Unilamellar Sphingomyelin-Phosphatidylcholine Vesicles: Effect of Altered Polar Head Group

IR@CDRI: CSIR-Central Drug Research Institute, Lucknow


Field	Value

Creator	Kumar, Ajay Gupta, C M

Date	2008-03-26T07:37:12Z 2008-03-26T07:37:12Z 1985

Identifier	Biochemistry (1985), 24, 5117-5163 http://hdl.handle.net/123456789/124

Description	The effect of the altered polar head group of phosphatidylcholine (PC) on its transbilayer distributions in small unilamellar vesicles containing sphingomyelin (SM) was ascertained with phospholipase A2 as the external membrane probe. These vesicles were formed by sonication and fractionated by centrifugation. The vesicle size was determined by gel-permeation chromatography and solute entrapment. Experiments were done to confirm that phospholipase A2 treatments did not induce fusion, lyse the vesicles, or cause PC to migrate across the vesicle bilayer. The complete degradation of external PC in intact vesicles was assured by carrying out the enzyme reactions in the absence as well as in the presence of 9.2 X 10-5 M bovine serum albumin. In small vesicles comprised of SM and 30 mol % 1,2-dipalmitoyl-sn-glycero- 3-phosphocholine(DPPC), DPPC preferentially distributed in the inner monolayer. This preference of DPPC in these vesiclesdisappeared upon introducing one C2H5 group at the carbon atom adjacent to the quaternary ammonium residue in its polar head group and was reversed when the C2H5 group was replaced by C6H5 and C6H5CH2 substituents or when the P-N distance was increased. These results indicate that the effective polar head-group volume is an important factor in determining the phospholipid distributions across the small vesicle bilayer.

Format	3199937 bytes application/pdf

Language	en

Relation	CDRI CommunicationNo. 3512

Title	Transbilayer Phosphatidylcholine Distributions in Small Unilamellar Sphingomyelin-Phosphatidylcholine Vesicles: Effect of Altered Polar Head Group

Type	Article