Interaction of bilirubin with gangliosides.
Gangliosides seem to play an important role in the interaction of the neurotoxic pigment bilirubin with the synaptosomal plasma membrane (Vázquez et al. [1988] J. Biol. Chem. 263, 1255-1265). In this report, a further characterization of the bilirubin-ganglioside interaction is presented. The interaction is fast, and it is observed at any pH in the range 7.0-9.0. The characteristics of the interaction are different from those observed with other membrane lipids, including sphingomyelin. A model of binding to a single population of sites is able to adequately fit the experimental data. This model predicts a decrease in the tendency of bilirubin to interact with gangliosides and an increase in the binding capacity as the pH is decreased from 8.0 to 7.0. Our data would suggest a role for gangliosides in explaining the preferential accumulation of bilirubin in some areas of the brain and the toxic effect of this pigment in neuronal membrane-related functions.
Vázquez
J
J
Departamento de Biología Molecular, Centro de Biología Molecular, UAM-CSIC, Universidad Autónoma de Madrid, Spain.
Ortega
G
G
Valdivieso
F
F
Mayor
F
F
D000818:Animals; D001663:Bilirubin / Q000378:metabolism*; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D003198:Computer Simulation; D005732:Gangliosides / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D013056:Spectrophotometry, Ultraviolet
D005732:Gangliosides; D001663:Bilirubin