Fracionamento e identificação de proteínas de linhaça dourada(Linum usitatissimum L.) associadas aos metais Cu, Fe e Zn

• Ano de defesa: 2015
• Autor(a) principal: Deyse de Brito Marthe
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: LC-MS/MS; Metal; Linhaca; GFAAS; Proteina; Química analítica; Síntese orgânica; Metais; Proteinas; Catalisadores
• Link de acesso: http://hdl.handle.net/1843/BUBD-A2KHYQ

Flaxseed (Linum usitatissimum L.) is known for its high nutritional value, mainly due to the high fiber, lignin and proteins content, which has beneficial health effects. Then, the goal of this work was to study the golden flaxseed proteins bound to the metals Cu, Fe and Zn. Initially, it was developed and validated a method to determinate metals in golden flaxseed samples using an acid digestion assisted by microwave radiation in a cavity system. The metals were quantified by flame atomic absorption spectrometry (FAAS). Digestion procedure was more efficient in a sample without oily fraction, so different brands of golden flaxseed without lipid fraction were analyzed. Iron obtained the highest concentration, followed by Zn and Cu, respectively. The polarity of the organic solvents can affected the metal-protein bound and disrupted it. In this sense, sample preparation was evaluated with different organic solvents, as hexane, chloroform and methanol. The content of Cu, Fe and Zn were higher in supernatants obtained after protein extraction in the sample without the lipid fraction using hexane as extractor. Proteins in these residues were also extracted by the sequential procedure and it was possible to relate the presence of albumin and globulins with the metals. After, the golden flaxseed oil phase was removed with hexane and the proteins were extracted in the lipid-free residue with Tris-HCl buffer solution to be fractionated in a molecular exclusion column chromatography. A protein fraction which higher absorbance and metals concentration was selected and analyzed by liquid chromatography-tandem mass spectrometry. Twenty-one proteins were identified including storage proteins. As procedures used were non-denaturing it is possible to say that the metals have a great affinity for the identified proteins. Another five golden flaxseed brands were submitted to protein extraction and it was observed by electrophoretic profile that they have different subunit composition. The protein levels obtained ranged from 2 to 6 mg ml-1 and the metals Cu, Fe and Zn were also quantified in these extracts, obtaining medium values of 50, 120 and 20 g L-1, respectively.