title: S-adenosylhomocysteine hydrolase from the thermophilic archaeon Sulfolobus solfataricus: purification, physico-chemical and immunological properties.
abstract: S-Adenosylhomocysteine hydrolase from Sulfolobus solfataricus, a thermoacidophilic archaeon optimally growing at 87 degrees C, has been purified to homogeneity. The specific activity of the homogeneous enzyme is 161 nmol of S-adenosylhomocysteine formed per min per mg of protein, and the overall yield, by immunoaffinity purification, is 51%. The enzyme has a molecular mass of 190 kDa, is composed of four identical subunits (subunit mass 47 kDa), and contains four molecules of tightly-bound NAD+ per tetramer of which about 40% is in the reduced form. Physico-chemical features, including amino-acid composition and secondary structure, are reported. The pure protein, used to raise specific rabbit antisera, shows immunological properties different from other S-adenosylhomocysteine-metabolizing enzymes. The enzyme is thermophilic with an optimum temperature of 75 degrees C, and shows an apparent melting temperature of 95 degrees C by measuring its residual activity after 10 min incubation at increasing temperatures.
authors.affiliation: Institute of Biochemistry of Macromolecules, Medical School, Second University of Naples, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Porcelli
authors.forename: G
authors.initials: G
authors.lastname: Cacciapuoti
authors.forename: S
authors.initials: S
authors.lastname: Fusco
authors.forename: G
authors.initials: G
authors.lastname: Iacomino
authors.forename: A
authors.initials: A
authors.lastname: Gambacorta
authors.forename: M
authors.initials: M
authors.lastname: De Rosa
authors.forename: V
authors.initials: V
authors.lastname: Zappia
mesh_terms: D043383:Adenosylhomocysteinase; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D004795:Enzyme Stability; D006358:Hot Temperature; D006867:Hydrolases / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D007106:Immune Sera / Q000276:immunology; D009243:NAD / Q000032:analysis; D017433:Protein Structure, Secondary; D011817:Rabbits; D016944:Sulfolobus / Q000201:enzymology*
chemical_list: D000596:Amino Acids; D007106:Immune Sera; D009243:NAD; D006867:Hydrolases; D043383:Adenosylhomocysteinase