The effect of some phenyltin compounds on the thermotropic phase behaviourand the structure of model membranes

The effects of diphenyltin dichloride (DPhT), triphenyltin chloride (TPhT) and tetraphenyltin (TTPhT) on the thermotropic phase behaviour of phosphati dylcholine bilayers were studied. All the phenyltin compounds investigated affected phase transitions differently. TTPhT broadened the main phase tran sition but it left the transition temperatures and enthalpy unchanged. TPhT reduced the transition temperatures and the enthalpies while DPhT showed a dual effect on the pretransition and the main transition. At low concentra tions DPhT reduced the temperatures of the transitions slightly and at high er concentrations it increased them. Based on differential scanning calorimetry (DSC) and also H-1 NMR and P-31 NMR measurements, it is suggested that DPhT induces interdigitated gel phas e formation and TPhT induces hexagonal phase formation, TTPhT seems to affe ct the structure only a little. The toxic activity of DPhT and TPhT seems t o be connected with their ability to induce changes in the membrane structu re. Copyright (C) 2000 John Wiley & Sons, Ltd.