In enzymology, a galactosylgalactosylglucosylceramidase () is an enzyme that catalyzes the chemical reaction D-galactosyl-D-galactosyl-D-glucosyl-N-acylsphingosine + H2O D-galactose + lactosyl-N-acylsphingosine Thus, the two substrates of this enzyme are D-galactosyl-D-galactosyl-D-glucosyl-N-acylsphingosine and H2O, whereas its two products are D-galactose and lactosyl-N-acylsphingosine. This enzyme belongs to the family of hydrolases, specifically those glycosidases that hydrolyse O- and S-glycosyl compounds. The systematic name of this enzyme class is D-galactosyl-D-galactosyl-D-glucosyl-N-acylsphingosine galactohydrolase. Other names in common use include trihexosyl ceramide galactosidase, ceramide trihexosidase, ceramidetrihexoside alpha-galactosidase, trihexosylceramide alpha-galactosidase, and ceramidetrihexosidase. References EC 3.2.1 Enzymes of unknown structure