Changes in the fluorescence characteristics of N-(1-pyrene) maleimide bound to the intestinal brush-border membranes by neuraminidase treatment

Abstract

The effects of neuraminidase treatment on the dynamic properties of the porcine intestinal brush-border membranes have been examined by using a fluorogenic thiol reagent, N-(1-pyrene)maleimide (NPM). Desialylation of the membranes by treatment with neuraminidase resulted in changes in the fluorescence parameters of NPM-labeled membranes, i.e. a decrease of the fluorescence lifetime and a suppression of the temperature-dependent decrease of the fluorescence intensity. These results suggest that the environmental properties around NPM-labeled SH groups in the membrane proteins were modified by neuraminidase treatment. Perturbation of the microenvironment around NPM-labeled SH groups associated with desialylation by the enzyme treatment was also determined by measuring the increase of fluorescence anisotropy and decrease of quenching efficiency with acrylamide or CH3COOTl of the complex. Based on the results, it is suggested that the dynamic properties of the conformation around NPM-labeled SH groups in the membrane proteins are sensitively influenced by neuraminidase treatment.