Biophysical and structural studies on aspartic proteases from pathogenic parasites. / Estudos biofísicos e estruturais de aspartil proteases de parasitas patogênicos.

AUTOR(ES)

Bruno de Lima Damasceno

DATA DE PUBLICAÇÃO

2008

RESUMO

The purpose of this study is to compare the structure of aspartic proteases of Plasmodium falciparum and Schistosoma mansoni in different chemical environments in order to provide relevant information for future rational design of new drugs and new knowledge about the folding and dynamism of structural proteins. For this, changes in secondary and tertiary structure of these proteases against chemical environments with denaturant condition (SDS), presence of a reducing agent (DTT), acidic and basic pHs were determined by the spectroscopy techniques of far UV circular dichroism spectroscopy (CD), and intrinsic fluorescence spectroscopy (IF). The results of these analyses showed qualitative and quantitative changes in the profile of secondary structures (alpha-helix, beta-sheet, and random structures) and the emissons behaviour of tryptophan of aspartic proteases studied, according to pH of the medium, the hydrophobic environment provided by SDS micelles or the environment provided by reducing DTT, thus indicating the presence of plasticity in these enzymes, possibly necessary for the achievement of its biological functions. In this work were also conducted studies of refolding an aspartic protease from S. mansoni (called proSmCD2) whose gene was recently cloned by our group. This enzyme was obtained in inclusion bodies from E. coli and different strategies were employed to achieve solubilization and refolding. It was possible to obtain this enzyme active after employed refolding by dilution in the presence of cosmotropic agents. The structural characterization by CD and IF revealed that the recombinant enzyme was obtained with structure compatible with the folding observed in other enzymes of the family of aspartic proteases pespin-like.

ASSUNTO(S)

biofísica biophysics proteins esquistossomose malaria malária schistosomiasis peptide hydrolases bioquimica proteínas peptídeo hidrolases

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