A serine carboxypeptidase from Trypanosoma cruzi.

FABIOLA PARUSSINI; MAYRA GARCÍA; JUAN MUCCI; DANIEL SÁNCHEZ; ULF HELLMAN; LENA ÅSLUND; JUAN JOSÉ CAZZULO

Lisboa

Congreso; 27th Meeting of Federation of European Biochemical Societies; 2001

Trypanosoma cruzi, the flagellate protozoan which is the causative of the American trypanosomiasis, Chagas diseases, has carboxypeptidase activity. the enzyme has been purified to rpotein homogeneity, and shown to be a lysosomal monomeric glycoprotein with a molecular mass of about 54 kDa. The enzyme has an optimum acidic pH (4.5 with furyl acryloyl Phe-Phe as substrate), is highly specific for hydrophobic C-terminal amino acid residues, and is strongly inhibited by 3,4-dichloroisocoumarin (IC50 value 0,3 microM). The enzyme is encoded by a number of genes arrayed in head to tail tandems, one of these genes has been cloned and sequenced. Sequence comparisons indicate that the enzyme belongs to the C group of serine carboxypeptidases, within the S10 serine peptidase family, and shows the higher similarity to planta and yeast enzymes. The residues involved in catalysis and most of those involved in substrate binding are conserved in the T. cruzi enzyme as well as 8 out of 10  Cys residues known to be involved in disulfide bridges in the yesat enzyme. This is the first report of an S10 family enzyme in trypanosomatids. The presence of serine carboxypeptidases is not restricted to T. cruzi, being possibly a general character of trypanosomatids.