Phospholipids and Oligomycin Sensitivity of Mitochondrial Adenosine Triphosphatase: a Spin Label Study

Abstract

There are observations suggesting that phospholipids are involved in the oligomycin sensitivity of mitochondria1 ATPase (adenosine triphosphatase) (Palatini & Bruni, 1970). Lenaz et al. (1971) have shown that alcohols make the mitochondria1 ATPase oligomycin insensitive, with an efficacy which is a function of alcohol chain length. This effect points out that hydrophobic bonds are involved in the inhibitor sensitivity of ATPase; a similar relation was found between alcohol chain length and phospholipid extractability, although higher alcohol concentrations were required for phospholipid extraction than for the effect on ATPase. I t was suggested that oligomycin sensitivity in mitochondria is related to the intactness of hydrophobic lipid-protein interactions. Electron spin resonance (e.s.r.) with spin-labelled lipids has become a very useful technique in probing the physical state of phospholipids in biological membranes (Hubbell & McConnell, 1968). In this communication we report the effect of butan-1-01 on the mobility of a 5-(4',4'-dimethyl-N-oxyloxazolidine) derivative of stearic acid in