Classificação estrutural de famílias de proteínas com base em mas de contatos.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The objective of this work was to verify if it is possible to classify protein chain structures using only the chemical interactions between its residues. Through contact maps and using three different metrics based on image processing techniques we have showed that we are able to classify such structures in families of similar structure and function with precision up to 99%. We have performed some experiments with attributes variation to find possible components of the structural signatures of each of the studied protein families. We have verified that some types of interactions are more discriminator then others (they are hydrogen bonds without water molecules in the middle of residues, hydrophobic contacts and ion-ion linking) and that other are less discriminator (hydrogen bonds intermediated by water molecules). We also have showed that contacts between residues which are sequentially close (less than 30 residues of distance) are not very discriminator attributes for classification, apparently being noises in the process. Moreover, for the preliminary results, the residues that form a great number of contacts are not more important that the less connected ones as one should previously think. Residues with few contacts apparently are essential in the definition of the structural signature of a family. We have showed that one of the techniques for contact maps comparison can additionally be useful as an heuristic for the contact map overlap problem. It can be used to align contact maps and through these alignments we can, for example, study mutations in residues that does not affect the pattern of contacts. We can compare mutant and wild proteins and also, comparatively study a protein of diverse animal species. Another important tested use of the technique is in the discovery of a pattern of interactions between different protein chains in complexes. In assays with serine-proteases and its inhibitors, the BPTIs, we have showed that it is possible to define a set of potentially important contacts in the binding and stabilization of the complexes. Some of the results of this work had been implemented and are available, beyond this site, in the STING (http://www.cbi.cnptia.embrapa.br/SMS). We participate of the conception and implementation of three different modules: PCD (Protein Contacts Difference), TopSiMap (Topology Similarity Map) and Topologs (a data base of similar structures being overcome as base only contacts).

ASSUNTO(S)

bioinformática teses. proteínas teses.

ACESSO AO ARTIGO

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