Alkaline Ceramidase: A ceramidase subtype that is active at alkaline pH. It is found at high levels within the SMALL INTESTINE.Ceramidases: Amidohydrolases that are specific for the cleavage of the N-acyl linkage of CERAMIDES. Ceramidases are classified as acidic, neutral or basic according to the optimal pH with which they function.Acid Ceramidase: A ceramidase subtype that is active at acid pH. It plays an important role in sphingolipid degradation by catalyzing the lysosomal hydrolysis of ceramide to sphingosine and free fatty acid. Inherited deficiency of acid ceramidase activity results in FARBER LIPOGRANULOMATOSIS.Neutral Ceramidase: A ceramidase subtype that is active at neutral pH. It is found at high levels within the SMALL INTESTINE and in the BRAIN.Galactosylgalactosylglucosylceramidase: An enzyme that catalyzes the hydrolysis of a ceramidetrihexoside to a ceramidedihexoside plus galactose.AmidohydrolasesCeramides: Members of the class of neutral glycosphingolipids. They are the basic units of SPHINGOLIPIDS. They are sphingoids attached via their amino groups to a long chain fatty acyl group. They abnormally accumulate in FABRY DISEASE.Sphingosine: An amino alcohol with a long unsaturated hydrocarbon chain. Sphingosine and its derivative sphinganine are the major bases of the sphingolipids in mammals. (Dorland, 28th ed)Substrate Specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.