Open AccessA recombinant tyrosine aminotransferase from Trypanosoma cruzi has both tyrosine aminotransferase and alanine aminotransferase activities
Author(s) -
Montemartini Marisa,
Búa Jacqueline,
Bontempi Esteban,
Zelada Cecilia,
Ruiz Andrés M.,
Santomé JoséA.,
JoséCazzulo Juan,
Nowicki Cristina
Publication year - 1995
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1995.tb07854.x
Subject(s) - tyrosine aminotransferase , tyrosine , biology , alanine , biochemistry , fusion protein , recombinant dna , microbiology and biotechnology , amino acid , trypanosoma cruzi , escherichia coli , enzyme , gene , enzyme inducer , parasite hosting , world wide web , computer science
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‐trans‐ferase. The purified fusion protein, intact or after thrombin cleavage, displays tyrosine aminotransferase and alanine aminotransferase activities with apparent K m values similar to those for the natural enzyme, thus proving that they belong to the same protein.