Spin-labeling study of phosphatidylcholine-cardiolipin binary mixtures

Abstract

EPR spectra of the spin-label probe 2,2,6,6-tetramethylpiperidinyl-1-oxyl were used to study the phase behavior of binary mixtures of different phosphatidylcholines (dipalmitoyl, distearoyl, and dioleoyl) with cardiolipin, using either Ca-free or Ca-containing cardiolipin (with a calcium:cardiolipin ratio of 1:2) samples. The nature of the fatty acid chains of the phosphatidylcholines (chain length and unsaturation) may influence the coexistence of different phases as well as does the nature of the cation linked to the cardiolipin.