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ESR spin probe and spin labelled studies of cardiolipin

University of British Columbia

The phospholipid, diphosphatidylglycerol (cardiolipin) forms liquid-crystalline phases having lamellar and hexagonal structures depending on the amount of water, the temperature and the presence of cations. ESR studies of cardiolipin in the lamellar and.the hexagonal phases using the 5-doxyl stearic acid spin probe were repeated to resolve a discrepency in the results reported in the literature. The spin probe was further used to follow the lamellar to hexagonal phase transition of cardiolipin as the Ca²⁺ concentration is increased from 0.0 to 50 mole % of Ca²⁺. Cardiolipin has been spin labelled at the polar head group by reaction with (2,2,5,5-tetramethylpyrroline-1-oxyl-3-carboxyl)-p-toluenesulfonate. The spin labelled cardiolipin (SLCL) was characterized using TLC and ESR. The SLCL was used in the ESR study of cardiolipin in the various phases. The results from this work indicate with the use of spin probes and spin labels, it is possible to distinguish the different phases of cardiolipin. Furthermore the results suggest that non-bilayer structures exist between 9 to 29 mole % of Ca²⁺. The data can be interpreted in terms of a temperature induced lateral phase separation of inverted micelles.

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2010-03-26

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http://hdl.handle.net/2429/22657

Chemistry

University of British Columbia

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