Spin-Labeled Phospholipids for Protein—Lipid Interactions

Abstract

Spin-labeled phospholipids constitute one of the most widespread classes of spin probes: derivatives of biologically active substances [1–4]. For assessing the biological activity of lipid fatty-acid probes, a number of experimental facts may be considered [2]: participation of spin-labeled fatty acids alongside with unlabeled ones in the biosynthesis of phospholipids by microorganisms [5], by enzymes of the liver microsomal fraction [6], and by other enzymatic systems [7]; participation in the catabolism of fatty acids (β-oxidation) [8]; in interaction with albumin [9]. In contrast to the case with spin-labeled fatty acids, the biological activity of spin-labeled phospholipids has not been studied adequately. In this chapter spin-labeled phospholipids are discussed from the standpoint as substrates for the phospholipase A2 and the participation of different spin-labeled phospholipids in protein-lipid interactions in biomembranes is considered. As is known, the role of hydrophobic protein-lipid interactions in the regulation of the enzymatic activity of integral proteins is extremely great [10]. Therefore, we were interested in studying the participation of spin-labeled phospholipids in these interactions, on the one hand, as evidence for their biological activity and, on the other hand, as a demonstration of the new avenues they open up in the applications of the method of spin probes.