Interaction of spectrin with phospholipids. Quenching of spectrin intrinsic fluorescence by phospholipid suspensions

Phospholipid suspensions prepared of phosphatidylethanolamine, phosphatidylserine and their mixtures are able to influence the intrinsic protein fluorescence of spectrin. In the case of phosphatidylethanolamine suspension up to 75% of protein fluorescence can be quenched. The interaction of phospholipid aggregates with spectrin is modulated by pH and ionic strength. Phospholipids, particularly phosphatidylethanolamine display a 'stabilizing' effect against the changes of protein fluorescence induced by increasing ionic strength and by thermal denaturation.