title: Comparison of liver glycosylasparaginases from six vertebrates.
abstract: Structural and physical properties of glycosylasparaginase (EC 3.5.1.26) from the livers of human, pig, cow, rat, mouse and chicken were compared. The enzyme in all species had a common basic structure of two N-glycosylated subunits of about 24 (alpha) and 20 (beta) kDa joined by non-covalent forces. Subunit-specific antisera against the rat glycosylasparaginase bound specifically and sensitively to the corresponding subunits from all species. Identity of 80% of the amino acids was found between the N-terminal sequences of corresponding pig and rat glycosylasparaginase alpha- and beta-subunits and the deduced sequence from a human glycosylasparaginase cDNA [Fisher, Tollersrud & Aronson (1990) FEBS Lett. 269, 440-444]. The beta-subunit from all three species has an N-terminal threonine reported to be involved in the reaction mechanism for the human enzyme [Kaartinen, Williams, Tomich, Yates, Hood & Mononen (1991) J. Biol. Chem. 266, 5860-5869]. The native enzyme appeared as a heterodimer among the mammals, whereas the chicken enzyme had a greater molecular mass and is probably either a tetramer or a heterodimer bound to an unrelated peptide(s). All glycosylasparaginases were thermostable, requiring temperatures between 65 degrees C and 80 degrees C to be irreversibly inactivated. In addition, they were unusually stable at high pH and remained active in the presence of SDS except at low pH. The pH maximum was between 5.5 and 6 except for the rat and mouse enzymes which had a broad maximum between pH 7 and 8. A number of other properties were observed which also distinguish the enzyme from individual and closely related species.
authors.affiliation: Department of Molecular and Cell Biology, Pennsylvania State University, University Park 16802.
authors.forename: O K
authors.initials: OK
authors.lastname: Tollersrud
authors.forename: N N
authors.initials: NN
authors.lastname: Aronson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001227:Aspartylglucosylaminase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D002417:Cattle; D002645:Chickens; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006031:Glycosylation; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015151:Immunoblotting; D007526:Isoelectric Point; D008099:Liver / Q000201:enzymology; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D013552:Swine
chemical_list: D046911:Macromolecular Substances; D001227:Aspartylglucosylaminase