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Title: Comparative Proteomic Analysis and IgE Binding Properties of Peanut Seed and Testa (Skin)

item White, Brittany
item GOKCE, EMINE - North Carolina State University
item NEPOMUCENO, ANGELITO - North Carolina State University
item MUDDIMAN, DAVID - North Carolina State University
item Sanders, Timothy
item Davis, Jack

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2013
Publication Date: 3/27/2013
Citation: White, B.L., Gokce, E., Nepomuceno, A.I., Muddiman, D.C., Sanders, T.H., Davis, J.P. 2013. Comparative Proteomic Analysis and IgE Binding Properties of Peanut Seed and Testa (Skin). Journal of Agricultural and Food Chemistry. 61(16)3957-3968.

Interpretive Summary: Peanut skins are a major waste product of the peanut processing industry, but they are a rich source of health-promoting phenolic compounds. Therefore, recent research has focused on identifying value-added food applications for this material, which otherwise has low economic value. Since peanuts are considered to be one of the eight major foods that cause allergic reactions, the allergenicity of peanut skins must be determined before they can be used as food ingredients. This study found that peanut skins contained the same allergenic proteins as the peanut seed. The ability of the proteins to bind peanut specific IgE, an antibody that recognizes allergenic proteins to begin the allergic reaction, was also determined. Peanut skin proteins bound IgE except when the naturally occurring phenolic compounds were present. This study suggests that peanut skins do contain allergenic proteins, but the presence of phenolic compounds may suppress their allergenicity.

Technical Abstract: To investigate the protein composition and potential allergenicity of peanut testae or skins, proteome analysis was conducted using nanoLC-MS/MS sequencing. Initial amino acid analysis suggested differences in protein compositions between the blanched seed (skins removed) and skin. Phenolic compounds hindered analysis of proteins in skins when the conventional extraction method was used; therefore, phenol extraction of proteins was necessary. A total of 123 proteins were identified in blanched seed and skins, and 83 of the proteins were common between the two structures. The skins contained all of the known peanut allergens in addition to 38 proteins not identified in the seed. Multiple defense proteins with antifungal activity were identified in the skins. Western blotting using sera from peanut allergic patients revealed that proteins extracted from both the seed and skin bound significant levels of IgE. However, when phenolic compounds were present in the skin protein extract, no IgE binding was observed. These findings indicate that peanut skins contain potentially allergenic proteins; however, the presence of phenolic compounds may attenuate this effect.