DISRUPTION OF MICELLAR AGGREGATES OF GANGLIOSIDE GM-1 BY COMPLEXATION WITH ALPHA-CYCLODEXTRIN

As previously observed for model glycolipids, micellar aggregates of the ganglioside GM-1 can be disrupted by the formation of inclusion complexes with cu-cyclodextrin ((alpha-CD). Evidence for such disaggregation was obtained from narrowing and shifting of H-1- and C-13-NMR signals, and decreasing of C-13-NMR relaxation times (T-1) upon addition of alpha-CD to aqueous (D2O) solutions of the ganglioside. As a result of the alpha-CD-induced disaggregation, GM-1 becomes permeable through 100 000 Da cut-off ultrafiltration membranes (which are virtually impermeable to normal GM-1 aggregates), and can be freed from phospholipid contaminants. beta-Cyclodextrin (beta-CD), which gives weaker complexes with GM-1, does not produce any significant disaggregation effects. Also, fully methylated beta-cyclodextrin (Me beta-CD) and hydroxyethyl-beta-cyclodextrin (HE beta-CD) were ineffective. A solid complex (which precipitates from solutions at alpha-CD/GM-1 molar ratios >5) was obtained, and characterized by CP/MAS C-13-NMR spectroscopy and by DSC.