A recombinant tyrosine aminotransferase from Trypanosoma cruzi has both tyrosine aminotransferase and alanine aminotransferase activities |
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Authors: | Marisa Montemartini,Jacqueline Bú a,Esteban Bontempi,Cecilia Zelada,ré s M. Ruiz,José A. Santomé ,Juan José Cazzulo,Cristina Nowicki |
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Affiliation: | IQUIFIB (UBA-CON/CET), Facultad de Farmacia v Bioquímica, Universidad de Buenos Aires, Junin 956, 1113 Buenos Aires, Argentina; Instituto National de Diagnóstico e Investigatión de la Enfermedad de Chagas 'Dr. Mario Fatala Chaben', Ministerio de Salud y Acción Social, Ar. Paseo Colon 563, 1063 Buenos Aires, Argentina; Instituto de Investigations Bioquímicas 'Luis F. Leloir', Fundatión Camponar, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. CONICET. A. Machado 151, 1405 Buenos Aires, Argentina |
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Abstract: | 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-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. |
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Keywords: | Tyrosine aminotransferase Alanine aminotransferase Trypanosoma cruzi Recombinant transaminase Fusion protein |
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