Purification and characterization of an endogenous inhibitor of the sialyltransferase CMP-N-acetylneuraminate: lactosylceramide alpha 2,6-N-acetylneuraminyltransferase (EC 2.4.99.-).

The presence in the 100,000 g supernatant of rat brain homogenate of an inhibitor of the sialyltransferase has been confirmed. It is also present in chicken and bovine brain and in other rat and bovine organs. The inhibitor has been purified, a preparation with a specific activity 130-fold higher than that of the original 100,000 g supernatant of brain being obtained.

Incorporation of sialyl groups into a brain unidentified compound with lipophilic properties.

Lactosylceramide (I), galactosylceramide (II) and lipids extracted from rat brain with methanol (III) were assayed as AcNeu acceptors from CMP-[3H] AcNeu. Rat brain microsomes in 3.2% Triton CF54 or the 100 000 g supernatant of these microsomes were used as enzyme source.

Changes of gangliosides and other lipids in skeletal muscle from rabbits with experimental dystrophy.

Comparison of the skeletal muscles from vitamin E-deficient and control rabbits showed that the muscles from the deficient animals had lower contents of protein and glycogen but more water and lipid. Increases of individual lipids per unit weight of muscle from deficient animals compared with those from control animals were 2.2-fold for gangliosides, 2.

Rabbit muscle gangliosides.

Four ganglioside fractions were isolated from rabbit muscle: one hematoside and three hexosamine-containing species. They were analyzed for hexoses, hexosamine, sialic acid, fatty acids, and long-chain base content. The molar ratios of sphingosine-hexose-hexosamine-sialic acid were: for hematoside, 1:2:0:1; for the disialogangliosides, 1:3:1:2; and for trisialoganglioside, 1:3:1:3.