Isolation and characterization of a new endo-beta-galactosidase from Diplococcus pneumoniae.
An endo-beta-galactosidase, which hydrolyzes the internal beta-galactosidic linkages of R----GlcNAc (or GalNAc) beta 1----3Gal beta 1----4GlcNAc (or Glc), was isolated from the culture supernatant of Diplococcus pneumoniae. The enzyme, named endo-beta-galactosidase DII, hydrolyzed linear N-acetyllactosamine repeating structures in glycolipids and glycopeptides to release oligosaccharides. The specificity of endo-beta-galactosidase DII is the same as that of Escherichia freundii endo-beta-galactosidase as far as described above, but the following differences between these two enzymes were found: Branched lactosaminyl glycolipids and H-antigenic glycolipids were resistant to endo-beta-galactosidase DII, even when linear structure was present at the inner part. Throughout the enzymic hydrolysis, endo-beta-galactosidase DII released mostly small oligosaccharides (tetra-, tri-, and disaccharides) from substrates, suggesting that the enzyme split off the oligosaccharides stepwise from the nonreducing terminal. Lactosaminoglycans were partially hydrolyzed by endo-beta-galactosidase DII to produce small oligosaccharides as the major product and residual glycopeptides. The residual glycopeptides were readily hydrolyzed by E. freundii endo-beta-galactosidase to produce various sizes of oligosaccharides. Keratan sulfate was not degraded by endo-beta-galactosidase DII. These properties of endo-beta-galactosidase DII characterize it as a new endo-beta-galactosidase with a unique specificity.
D001457:Anion Exchange Protein 1, Erythrocyte / Q000378:metabolism; D002236:Carbohydrate Conformation; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D004912:Erythrocytes / Q000201:enzymology; D005696:Galactosidases / Q000302:isolation & purification*; D006017:Glycolipids / Q000378:metabolism; D006026:Glycoside Hydrolases; D006801:Humans; D007632:Keratan Sulfate / Q000378:metabolism; D013296:Streptococcus pneumoniae / Q000201:enzymology*; D001616:beta-Galactosidase / Q000302:isolation & purification*
D001457:Anion Exchange Protein 1, Erythrocyte; D006017:Glycolipids; D007632:Keratan Sulfate; D005696:Galactosidases; D006026:Glycoside Hydrolases; C026093:keratan-sulfate endo-1,4-beta-galactosidase; D001616:beta-Galactosidase