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Abstract(s)
A bioinformática é uma disciplina inovadora que conheceu um grande
desenvolvimento nestes últimos anos. Ela não só permite uma real economia para a indústria
farmacêutica como também evita parte do sacrifício das espécies de animais habitualmente
usadas nos laboratórios de investigação científica.
Com o intuito de prever a estrutura secundária (hélices-α; folhas-β e voltas) das
proteínas a partir de escalas de hidrofobicidade dos aminoácidos, recorreu-se a ferramentas
informáticas, (Folhas de cálculo). Mais concretamente, utilizou-se vários métodos de cálculo
como a escala de hidrofobicidade de Kyte & Doolittle entre outras; método de Chou & Fasman
e método de Lupas. Também foi estudada a presença de zonas de maior alergenicidade nas
proteínas. Estes estudos foram efectuados com as seguintes proteínas: lisozima C;
ovalbumina; ovomucina; ovomucóide; α -caseína s1; α-caseína s2; β-caseína; β-
lactoglobulina; β-2-microglobulina; osteopontina e ubiquitina. Os cálculos foram também
efectuados para a BSA.
A interpretação dos resultados obtidos não foi tão fácil quanto o esperado. Se o
método de Chou & Fasman e o método de Lupas não deixam margem de dúvida quanto à
possível existência de estruturas como: as hélices-α; folhas-β e voltas (turns) ou ainda a
super-hélices-α (coiled-coil), não se pode esquecer que se trata de métodos baseados em
cálculos de probabilidade. Por essa razão, não permitem dizer com toda a certeza qual a
estrutura secundária das proteínas em estudo. Os resultados gráficos obtidos através dos
cálculos baseados nas escalas de hidrofobicidade, revelaram uma falta de clareza e evidência
sendo mesmo por vezes sujeitos a interpretações subjectivas. No estudo da alergenicidade,
também ele baseado numa escala de hidrofobicidade (escala de Hopp & Wood), todos os picos
obtidos podem ser interpretados como potenciais zonas de ligação ou seja, potenciais
epítopos visto que têm valores positivos.
De um ponto de vista geral, pode dizer-se que todos os métodos utilizados,
encontraram aplicação em todas as proteínas estudadas. No entanto, é preciso ter-se em
conta que todos os resultados são apresentados como se as proteínas estivessem totalmente
desenroladas, o que não é conforme à realidade.
Bioinformatics is an innovative discipline that has been significantly developed in the past few years. It not only allows a real economy for the pharmaceutical industry, but also avoids the sacrifice of the animal species usually used in scientific investigation laboratories. Informatic tools were used with the objective of predicting the secondary structure (α-helices, β-sheets and turns) of proteins from aminoacids hydrophobicity scales. Specifically, several calculation methods were used like the Kyte & Doolittle hydrophobicity scale, among other scales, Chou & Fasman method and Lupas method. The presence of larger alergenecity areas in proteins was also studied. These studies were performed using the following proteins: lysozyme C, ovalbumin, ovomucin, ovomucoid, α–casein s1, α–casein s2, β- casein, β-lactoglobulin, β-2-microglobulin, osteopontin and ubiquitin. Calculations were also preformed with BSA. The interpretation of the obtained results was not as easy as expected. If Chou & Fasman and Lupas methods did not raise any doubts to the possible existence of structures like α-helices, β-sheets and turns or even coiled-coil α-helices, it cannot be disregard that these are probability based methods. For this reason it is not possible to predict with absolute certainty the secondary structure of the studied proteins. The graphic results obtained by calculations based on the hydrophobicity scales reveal a lack of clarity and evidence, and were sometimes object of incorrect interpretations. In the allergenicity study, also based in the Hopp & Wood hydrophobicity scale, all the obtained peaks could be interpreted as potential binding areas, or epitopes, since they have positive values. In a broad point of view, it can be concluded that all the used methods find application in the studied proteins. However, the study was made considering that the proteins are totally unwind, which does not correspond to reality.
Bioinformatics is an innovative discipline that has been significantly developed in the past few years. It not only allows a real economy for the pharmaceutical industry, but also avoids the sacrifice of the animal species usually used in scientific investigation laboratories. Informatic tools were used with the objective of predicting the secondary structure (α-helices, β-sheets and turns) of proteins from aminoacids hydrophobicity scales. Specifically, several calculation methods were used like the Kyte & Doolittle hydrophobicity scale, among other scales, Chou & Fasman method and Lupas method. The presence of larger alergenecity areas in proteins was also studied. These studies were performed using the following proteins: lysozyme C, ovalbumin, ovomucin, ovomucoid, α–casein s1, α–casein s2, β- casein, β-lactoglobulin, β-2-microglobulin, osteopontin and ubiquitin. Calculations were also preformed with BSA. The interpretation of the obtained results was not as easy as expected. If Chou & Fasman and Lupas methods did not raise any doubts to the possible existence of structures like α-helices, β-sheets and turns or even coiled-coil α-helices, it cannot be disregard that these are probability based methods. For this reason it is not possible to predict with absolute certainty the secondary structure of the studied proteins. The graphic results obtained by calculations based on the hydrophobicity scales reveal a lack of clarity and evidence, and were sometimes object of incorrect interpretations. In the allergenicity study, also based in the Hopp & Wood hydrophobicity scale, all the obtained peaks could be interpreted as potential binding areas, or epitopes, since they have positive values. In a broad point of view, it can be concluded that all the used methods find application in the studied proteins. However, the study was made considering that the proteins are totally unwind, which does not correspond to reality.
Description
Keywords
Proteínas Proteínas - Hidrofobicidade Proteínas - Alergenicidade Proteínas - Estrutura secundária Epítopos Bioquímica - Bioinformática
Citation
Publisher
Universidade da Beira Interior