Evidence for Penetration in Liposomes and in Mitochondrial Membranes of a Fluorescent Analogue of Cord Factor

A fluorescent analogue of cord factor, a glycolipid toxin of mycobacteria, has been synthesized and its interactions with liposomes and isolated mitochondria have been studied. This compound, methyl alpha-D-612-(9-anthroyl)stearoylglucoside, is shown to be active against oxidative phosphorylation. When spread as a monolayer at the air-water interface, it forms a well organized phase and it strongly interacts with phosphatidylcholine. Addition of phosphatidylcholine liposomes or of isolated mitochondria to a water disperson of this fluorescent cord factor analogue results in a large increase of the fluorescence intensity. Moreover, the glycolipid probes for the temperature-dependent phase transition of the added suspensions. It is thus suggested that this cord factor analogue penetrates within mitochondrial membranes, a result which is discussed with respect to our previous conclusions concerning the way natural cord factors can interact with these organelles.