title: Purification and characterization of alpha-galactosidase from watermelon.
abstract: An alpha-galactosidase [EC 3.2.1.22] was isolated from the fruit of the watermelon, Citrullus battich. The enzyme was purified by procedures including extraction, ammonium sulfate precipitation, and chromatographies on DEAE-Sephadex, CM-Sephadex and Sephadex G-100. The final preparation was found to be fairly homogeneous on disc and SDS-polyacrylamide gel electrophoresis, and sufficiently free from other glycosidase activities. The molecular weight of the enzyme was estimated to be 45,000 by Sephadex G-100 column chromatography and SDS-polyacrylamide gel electrophoresis. The enzyme was most active at pH 4.5 for natural substrates and at 5.9 for artificial substrates. The enzyme liberates the alpha-galactose units from oligosaccharides of the raffinose series and ceramide trihexoside, and the hemagglutination-inhibiting activities of human ovarian cyst B-glycoprotein and blood group B-type ghosts were abolished by the enzyme.
mesh_terms: D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D005260:Female; D005696:Galactosidases / Q000302:isolation & purification*; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008970:Molecular Weight; D010048:Ovarian Cysts / Q000378:metabolism; D010944:Plants / Q000201:enzymology*; D014281:Trihexosylceramides / Q000378:metabolism; D000519:alpha-Galactosidase / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D006023:Glycoproteins; D014281:Trihexosylceramides; D005696:Galactosidases; D000519:alpha-Galactosidase