Isolation and characterization of ceramide glycanase

Ceramide glycanase is an enzyme which hydrolyzes the linkage between the oligosaccharide chains and lipid moieties of glycolipids. The intact glycan chains are released from various glycolipids in which the glycan chains are attached to the lipid moieties through a $\beta$-glucosyl linkage. This dissertation includes isolation and characterization of ceramide glycanase from leeches and earthworms and brief examination of the distribution of this unique lipid splitting enzyme in certain living organisms and tissues.

Ceramide glycanase was isolated from the leech, Macrobdella decora. The general properties of the purified enzyme and its relative activities on various natural glycosphingolipids were carefully characterized. The rate of the hydrolysis by this enzyme on various glycolipids either having the same oligosaccharide chains but differing in the lipid moieties or having the same lipid portions but differing in the sugar chains was compared. The results indicated that both the hydrophilic and hydrophobic moieties in glycolipids affect the action of ceramide glycanase.

Additionally, ceramide glycanase was purified from the earthworm, Lumbricus terrestris and its properties were compared with those of the leech enzyme. Although they differ somewhat in molecular weight, optimal pH, sensitivity to metal ions, detergent requirement and substrate specificities, both enzymes hydrolyze various glycolipids including ceramide glycans (glycosphingolipids), sphingosine glycans (lyso-glycosphingolipids), alkyl-glycans and dialkylglycerol which have oligosaccharide chains linked to the lipid moieties through a $\beta$-glucosyl linkage.

Among all the plants, animals and mammalian tissues and organs examined, ceramide glycanase was found only in annelids. No ceramide glycanase activity has been detected in any tissues or organs from mammalian sources.