Cerebroside galactosidase of brain

The galactoside bond in cerebroside was found to be cleaved by an enzyme in rat and pig brain. Emulsified stearoyl-1% psychosine was used as the substrate and the extent of cleavage was studied by isolating and counting the stearoyl sphingosine (ceramide) formed. The reaction products, cer- amide and galactose, were characterized by column and thin- layer chromatography. Cerebroside containing gala~tose-~H was also used to show liberation of galactose. Cholic acid was found to be required for activation of the enzyme, which has a pH optimum of 4.5. Similar cerebrosidase activity was found in spleen, kidney, and lung of rat; liver and heart showed very slight activity. The partially purified enzyme from pig brain also formed ceramide from ceramide lactoside, ceramide glucoside, and cerebronoyl psychosine. The enzyme was active toward o- nitrophenyl galactoside and could be fractionated by Sephadex chromatography into a fraction active toward the nitrophenyl galactoside only and a fraction active toward both this sub- strate and ceramide galactoside. Human spleen, normal and Gaucher, exhibited cerebrosidase activity.