title: A recombinant tyrosine aminotransferase from Trypanosoma cruzi has both tyrosine aminotransferase and alanine aminotransferase activities.
abstract: Tyrosine aminotransferase purified from epimastigotes of Trypanosoma cruzi displays an additional activity of alanine aminotransferase, absent in all other tyrosine aminotransferases characterized so far. Since the parasite's genome contains a high number of copies of the tyrosine aminotransferase gene, we could not rule out the possibility that two very similar proteins, with changed specificity due to a few amino acid substitutions, might be responsible for the two activities. We have now expressed in Escherichia coli a recombinant tyrosine aminotransferase as a fusion protein with glutathione S-transferase. The purified fusion protein, intact or after thrombin cleavage, displays tyrosine aminotransferase and alanine aminotransferase activities with apparent Km values similar to those for the natural enzyme, thus proving that they belong to the same protein.
authors.affiliation: IQUIFIB (UBA-CONICET), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina.
authors.forename: M
authors.initials: M
authors.lastname: Montemartini
authors.forename: J
authors.initials: J
authors.lastname: Búa
authors.forename: E
authors.initials: E
authors.lastname: Bontempi
authors.forename: C
authors.initials: C
authors.lastname: Zelada
authors.forename: A M
authors.initials: AM
authors.lastname: Ruiz
authors.forename: J A
authors.initials: JA
authors.lastname: Santomé
authors.forename: J J
authors.initials: JJ
authors.lastname: Cazzulo
authors.forename: C
authors.initials: C
authors.lastname: Nowicki
mesh_terms: D000410:Alanine Transaminase / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D004926:Escherichia coli / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D005982:Glutathione Transferase / Q000235:genetics; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000235:genetics; D014349:Trypanosoma cruzi / Q000201:enzymology / Q000235:genetics*; D014444:Tyrosine Transaminase / Q000235:genetics* / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D005982:Glutathione Transferase; D000410:Alanine Transaminase; D014444:Tyrosine Transaminase