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Carbon-Centered Radicals in Isolated Soy Proteins

Authors

  • W.L. Boatright,

    1. Authors Boatright and Lei are with Dept. of Animal and Food Sciences, Univ. of Kentucky, 412 W.P. Garrigus Building, Lexington, KY 40546-0215, U.S.A. Authors Jahan and Walters are with Dept. of Physics, Univ. of Memphis, 216 Manning Hall, Memphis, TN 38152, U.S.A. Authors Miller and Cui are with Dept. of Chemistry, Univ. of Kentucky, 113 Chemistry-Physics Building, Lexington, KY 40506-0055, U.S.A. Author Hustedt is with Dept. of Molecular Physiology & Biophysics, Vanderbilt Univ. School of Medicine, 702 Light Hall, Nashville, TN 37232, U.S.A. Direct inquiries to author Boatright (E-mail: wlboat1@uky.edu).
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  • M.S. Jahan,

    1. Authors Boatright and Lei are with Dept. of Animal and Food Sciences, Univ. of Kentucky, 412 W.P. Garrigus Building, Lexington, KY 40546-0215, U.S.A. Authors Jahan and Walters are with Dept. of Physics, Univ. of Memphis, 216 Manning Hall, Memphis, TN 38152, U.S.A. Authors Miller and Cui are with Dept. of Chemistry, Univ. of Kentucky, 113 Chemistry-Physics Building, Lexington, KY 40506-0055, U.S.A. Author Hustedt is with Dept. of Molecular Physiology & Biophysics, Vanderbilt Univ. School of Medicine, 702 Light Hall, Nashville, TN 37232, U.S.A. Direct inquiries to author Boatright (E-mail: wlboat1@uky.edu).
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  • B.M. Walters,

    1. Authors Boatright and Lei are with Dept. of Animal and Food Sciences, Univ. of Kentucky, 412 W.P. Garrigus Building, Lexington, KY 40546-0215, U.S.A. Authors Jahan and Walters are with Dept. of Physics, Univ. of Memphis, 216 Manning Hall, Memphis, TN 38152, U.S.A. Authors Miller and Cui are with Dept. of Chemistry, Univ. of Kentucky, 113 Chemistry-Physics Building, Lexington, KY 40506-0055, U.S.A. Author Hustedt is with Dept. of Molecular Physiology & Biophysics, Vanderbilt Univ. School of Medicine, 702 Light Hall, Nashville, TN 37232, U.S.A. Direct inquiries to author Boatright (E-mail: wlboat1@uky.edu).
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  • A.F. Miller,

    1. Authors Boatright and Lei are with Dept. of Animal and Food Sciences, Univ. of Kentucky, 412 W.P. Garrigus Building, Lexington, KY 40546-0215, U.S.A. Authors Jahan and Walters are with Dept. of Physics, Univ. of Memphis, 216 Manning Hall, Memphis, TN 38152, U.S.A. Authors Miller and Cui are with Dept. of Chemistry, Univ. of Kentucky, 113 Chemistry-Physics Building, Lexington, KY 40506-0055, U.S.A. Author Hustedt is with Dept. of Molecular Physiology & Biophysics, Vanderbilt Univ. School of Medicine, 702 Light Hall, Nashville, TN 37232, U.S.A. Direct inquiries to author Boatright (E-mail: wlboat1@uky.edu).
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  • D. Cui,

    1. Authors Boatright and Lei are with Dept. of Animal and Food Sciences, Univ. of Kentucky, 412 W.P. Garrigus Building, Lexington, KY 40546-0215, U.S.A. Authors Jahan and Walters are with Dept. of Physics, Univ. of Memphis, 216 Manning Hall, Memphis, TN 38152, U.S.A. Authors Miller and Cui are with Dept. of Chemistry, Univ. of Kentucky, 113 Chemistry-Physics Building, Lexington, KY 40506-0055, U.S.A. Author Hustedt is with Dept. of Molecular Physiology & Biophysics, Vanderbilt Univ. School of Medicine, 702 Light Hall, Nashville, TN 37232, U.S.A. Direct inquiries to author Boatright (E-mail: wlboat1@uky.edu).
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  • E.J. Hustedt,

    1. Authors Boatright and Lei are with Dept. of Animal and Food Sciences, Univ. of Kentucky, 412 W.P. Garrigus Building, Lexington, KY 40546-0215, U.S.A. Authors Jahan and Walters are with Dept. of Physics, Univ. of Memphis, 216 Manning Hall, Memphis, TN 38152, U.S.A. Authors Miller and Cui are with Dept. of Chemistry, Univ. of Kentucky, 113 Chemistry-Physics Building, Lexington, KY 40506-0055, U.S.A. Author Hustedt is with Dept. of Molecular Physiology & Biophysics, Vanderbilt Univ. School of Medicine, 702 Light Hall, Nashville, TN 37232, U.S.A. Direct inquiries to author Boatright (E-mail: wlboat1@uky.edu).
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  • Q. Lei

    1. Authors Boatright and Lei are with Dept. of Animal and Food Sciences, Univ. of Kentucky, 412 W.P. Garrigus Building, Lexington, KY 40546-0215, U.S.A. Authors Jahan and Walters are with Dept. of Physics, Univ. of Memphis, 216 Manning Hall, Memphis, TN 38152, U.S.A. Authors Miller and Cui are with Dept. of Chemistry, Univ. of Kentucky, 113 Chemistry-Physics Building, Lexington, KY 40506-0055, U.S.A. Author Hustedt is with Dept. of Molecular Physiology & Biophysics, Vanderbilt Univ. School of Medicine, 702 Light Hall, Nashville, TN 37232, U.S.A. Direct inquiries to author Boatright (E-mail: wlboat1@uky.edu).
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Abstract

ABSTRACT:  Solid-state electron paramagnetic resonance (EPR) spectroscopy of commercial samples of isolated soy proteins (ISP) revealed a symmetrical free-radical signal typical of carbon-centered radicals (g= 2.005) ranging from 2.96 × 1014 to 6.42 × 1014 spins/g. The level of free radicals in ISP was 14 times greater than similar radicals in sodium caseinate, 29 times greater than egg albumin, and about 100 times greater levels than casein. Nine soy protein powdered drink mixes contained similar types of free radicals up to 4.10 × 1015 spins/g of drink mix, or up to 6.4 times greater than the highest free-radical content found in commercial ISP. ISP samples prepared in the laboratory contained trapped radicals similar to the levels in commercial ISP samples. When ISP was hydrated in 2.3 mM sodium erythorbate or 8.3 mM L-cysteine, frozen and dried, the level of trapped free radicals increased by about 17- and 19-fold, respectively. The ESR spectrum of defatted soybean flakes contained overlapping signals from the primary free-radical peak (g= 2.005) and a sextet pattern typical of manganese-II. The manganese signal was reduced in the laboratory ISP and very weak in the commercial ISP.

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