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Conformation of α zeins in solid state by Fourier transform IR

Conformation of α zeins in solid state by Fourier transform IR The major maize storage proteins (α 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 α zein structure by alcohol, we analyze the secondary structure of α zeins prepared with and without solubilization in alcohol (corn gluten meal and protein bodies with high concentrations of α zeins and traces of β zeins). The secondary structures of α zeins are analyzed in the solid state by Fourier transform IR spectroscopy (FTIR) in KBr pellets and solid‐state 13C‐NMR spectroscopy. The proportion of secondary structures obtained by FTIR of α zeins prepared with and without solubilization in alcohol yield almost identical proportions of α helices and β sheets. The proportion of α helices (43%) agrees with that measured by circular dichroism in an alcohol solution. However, the proportion of β sheets (28%) is higher than the one measured by the same technique. Gluten and protein body samples with high β zein content showed higher β sheet and lower α helix proportions than that obtained for α zein preparations. The solid‐state 13C‐NMR spectra show the carbonyl peak for the α zeins at δ 176 and for the sample rich in β zeins at δ 172, which demonstrates the presence of a high content of α helices and β sheets, respectively. These results indicate that alcohol solubilization does not affect the conformation of α zeins, validating the secondary structure measurements in solution. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy), 2003 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Biopolymers Wiley

Conformation of α zeins in solid state by Fourier transform IR

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References (21)

Publisher
Wiley
Copyright
Copyright © 2003 Wiley Periodicals, Inc., A Wiley Company
ISSN
0006-3525
eISSN
1097-0282
DOI
10.1002/bip.10481
pmid
14587064
Publisher site
See Article on Publisher Site

Abstract

The major maize storage proteins (α 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 α zein structure by alcohol, we analyze the secondary structure of α zeins prepared with and without solubilization in alcohol (corn gluten meal and protein bodies with high concentrations of α zeins and traces of β zeins). The secondary structures of α zeins are analyzed in the solid state by Fourier transform IR spectroscopy (FTIR) in KBr pellets and solid‐state 13C‐NMR spectroscopy. The proportion of secondary structures obtained by FTIR of α zeins prepared with and without solubilization in alcohol yield almost identical proportions of α helices and β sheets. The proportion of α helices (43%) agrees with that measured by circular dichroism in an alcohol solution. However, the proportion of β sheets (28%) is higher than the one measured by the same technique. Gluten and protein body samples with high β zein content showed higher β sheet and lower α helix proportions than that obtained for α zein preparations. The solid‐state 13C‐NMR spectra show the carbonyl peak for the α zeins at δ 176 and for the sample rich in β zeins at δ 172, which demonstrates the presence of a high content of α helices and β sheets, respectively. These results indicate that alcohol solubilization does not affect the conformation of α zeins, validating the secondary structure measurements in solution. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy), 2003

Journal

BiopolymersWiley

Published: Jan 1, 2003

Keywords: conformation; α zeins; solid state; secondary structures; Fourier transform IR spectroscopy; NMR

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