Property and Activity of Mycoloyl Esters of Methyl Glucoside and Trehalose

Abstract

Methyl .alpha.-D-glucoside and .alpha.,.alpha.''-D-trehalose acylated on their primary hydroxyl group by .alpha.-alkyl-.beta.-hydroxy acids (mycolic acids) with 18, 32 and more than 80 C atoms were studied. These cord factors [which can be found in mycobacteria, corynebacteria and nocardias] and analogs gave hydrated and organized phases when dispersed in water, which bore resemblances and differences to phospholipid liposomes. Phase transition temperature was determined by fluorescence for the C32 derivatives and by differential scanning calorimetry for the C80 derivatives. A narrow temperature interval between the gel and the fluid states was observed, indicating that this transition was a strongly cooperative phenomenon. The activity on [rat liver] mitochondria of these diacyl trehaloses was studied with succinate as substrate. The fluid suspensions were more active than the rigid ones. There was no influence of the relative configuration of the mycoloyl residue. Acyl chains with 18, 32 and more than 80 C atoms had rather similar activities on phosphorylation, but differences appeared when considering effects on respiration. EM suggested that cord factor weakened the peripheral part of the inner membrane, but cristae looked unchanged. A model was proposed for interaction of cord factor with mitochondria.