AGGREGATION PROPERTIES OF SEMISYNTHETIC GD1A GANGLIOSIDE (IV(3)NEU5ACII(3)NEU5ACGGOSE(4)CER) CONTAINING AN ACETYL GROUP AS ACYL MOIETY

GD1a ganglioside containing an acetyl group as acyl moiety, GD1a(acety l), was synthesized from natural GD1a. The aggregative properties in a queous solution of GD1a(acetyl) have been studied by static and dynami c laser light-scattering measurements. GD1a(acetyl) spontaneously aggr egates as small micelles showing a hydrodynamic radius and molecular m ass of 33 Angstrom and 96 kDa, respectively. Vibrio cholerae sialidase showed a very high activity on the micelles of GD1a(acetyl), compared to GD1a. This has been explained as a consequence of the high surface curvature of the the small micelles. High resolution proton NMR spect ra were recorded from micelles of GD1a(acetyl) in deuterated water. Th e low overall correlation time of the GD1a(acetyl) micelles was calcul ated to be about 2 x 10(-8) s, a value one order of magnitude lower th an that determined for natural GD1a.