Tetrameric and dimeric malate dehydrogenase isoenzymes in Trypanosoma cruzi epimastigotes.
Mol Biochem Parasitol
; 105(2): 203-14, 2000 Feb 05.
Article
em En
| MEDLINE
| ID: mdl-10693743
Two malate dehydrogenase isoforms, named MDH1 and MDH2, have been purified to homogeneity from Trypanosoma cruzi epimastigotes. Both enzymes consist of subunits with a molecular mass close to 33 kDa; native molecular mass determination by gel filtration, however, indicated that MDH1 is a dimer, whereas MDH2 is a tetramer. Both isoforms did not cross-react immunologically. The N-termini of both MDH isoforms and several tryptic peptides of MDH1 (amounting to about one third of the complete molecule) have been sequenced by automated Edman degradation. The tryptic digests of both enzymes have also been analysed by mass spectrometry (MALDI-TOF MS). The apparent Km values in both directions of the reaction have been determined, as well as the possible inhibition by excess of the substrate oxaloacetate. The sequence data, together with the pI values and the presence or absence of oxaloacetate inhibition indicate that the dimeric MDH1 is the mitochondrial isoenzyme, whereas the tetrameric MDH2 is the glycosomal isoenzyme. No evidence was found for the presence of a cytosolic isoform.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Trypanosoma cruzi
/
Isoenzimas
/
Malato Desidrogenase
Limite:
Animals
Idioma:
En
Revista:
Mol Biochem Parasitol
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
Argentina
País de publicação:
Holanda