Data/hora: 21/06/2024 05:21:44

Biblioteca(s): | Embrapa Instrumentação.
Data corrente: | 23/03/2005
Data da última atualização: | 23/03/2005
Autoria: | FORATO, L. A.; BICUDO, T. C.; COLNAGO, L. A.
Título: | Conformation of alfa Zeins in solid state by fourier Transform IR.
Ano de publicação: | 2003
Fonte/Imprenta: | Biopolymers (Biospectroscopy), v. 72, 421-426, 2003.
Idioma: | Inglês
Conteúdo: | ABSTRACT: The major maize storage proteins (alpha zeins) are deposited as an insoluble mass in the protein bodies of the endosperm. Because they are insoluble in water, most structural studies are performed in alcohol solutions. To solve the question raised by several authors about denaturation of the a zein structure by alcohol, we analyze the secondary structure of a zeins prepared with and without solubilization in alcohol (corn gluten meal and protein bodies with high concentrations of a zeins and traces of beta zeins). The secondary structures of a zeins are analyzed in the solid state by Fourier transform IR spectroscopy (FTIR) in KBr penets and solid-state 13C-NMR spectroscopy. The proportion of secondary structures obtained by FTIR of a zeins prepared with and without solubilization in alcohol yield almost identical proportions of a helices and (3 sheets. The proportion of a helices (43%) agrees with that measured by circular dichroism in an alcohol solution. However, the proportion of beta sheets (28%) is higher than the one measured by the same technique. Gluten and protein body samples with high beta zein content showed higher beta sheet and lower a helix proportions than that obtained for a zein preparations. The solid-state 13C-NMR spectra show the carbonyl peak for the a zeins at Delta 176 and for the sample rich in beta zeins at gama 172, which demonstrares the presence of a high C9ntent of a helices and beta sheets, respectively. These results indicare that alcohol solubilization does not affect the conformation of a zeins, validating the secondary structure measurements in solution.
Palavras-Chave: | alfa Zeins; Conformação; Estado sólido; Estrutura Secundárias; NMR; Spectroscopia IR Fourier.
Categoria do assunto: | --
Registro original: | Embrapa Instrumentação (CNPDIA)
Exemplares: | CNPDIA - (8740-1) - UPC - SP - -- - PROCI-03.00085 -  - 2003.00085 - DIS