Monoclonal antibody MACG1 distinguishes between different molecular species of the ganglioside GM3.

The present study investigates the chemical structure of a ganglioside, detected by monoclonal antibody (MAb) MacG1, which reacts with intracytoplasmic granules of tumor-infiltrating macrophages. The results obtained by enzymatic hydrolysis and fast-atom bombardment-mass spectrometry reveal that MAb MacG1 reacts with a subcomponent of the ganglioside GM3 found in melanoma and bovine brain. MAb MacG1 might be a powerful tool to distinguish among GM3 species and could help to define their possibly different biological functions.

Studies on bovine brain membrane-bound neuraminidase (sialidase).

1) Lipophilic ganglioside GD1a (IV3NeuAc, II3NeuAc-GgOse4-Cer) is taken up by the cell membranes and hydrolyzed faster by membrane-bound neuraminidase than are water soluble substrates of the enzyme. 2) The enzymic breakdown of ganglioside GD1a is enhanced by general anesthetics whereas the degradation of the hydrophilic substrate sialyllactitol is reduced by these same agents. 3) General anesthetics lower the microviscosity of membranes as indicated by studies of fluorescence depolarisation with the indicator 1,6-diphenylhexatrien.