46I-18 |
Antigenic proteins in almond, cashew nut and walnut are not resistant to in vitro proteolysis |
M. VENKATACHALAM1, S. S. Teuber2, K. H. Roux3, and S. K. Sathe1. (1) Department of Nutrition, Food and Exercise Sciences, Florida State University, 402 Sandels Bldg., College of Human Sciences, Tallahassee, FL 32306-1493, (2) Division of Rheumatology, Allergy and Clinical Immunology, University of California, Davis, CA 95616, (3) Department of Biological Science, Florida State University Several investigators have suggested that for a food protein to be an allergen, it must be resistant to proteolysis. During the course of our on-going investigations on tree nut proteins and tree nut-induced allergies, we noted that almond, cashew, and walnut proteins are highly digestible when subjected to in vitro proteolysis under a variety of conditions. It was therefore important to learn whether these tree nut proteins retain their antigenicity after being exposed to in vitro proteolysis. Simulated gastric fluid (SGF) digestion commonly accepted as a suitable method for evaluating the allergenicity of proteins was used for digestibility studies. Proteins were extracted from defatted almond, cashew and walnut flour with distilled deionized water (pH adjusted to 8.5), Lowry protein content determined and 0.25 mg of protein/ml of SGF used for digestion at 37oC. Aliquots of digested protein samples were drawn periodically over a period of 60 minutes, pepsin activity terminated and antigenic stability evaluated by Western blotting and inhibition enzyme linked immunosorbent assays (ELISAs) using rabbit polyclonal antibodies raised against the major proteins from almond, cashew nut, and walnut. The results suggest that almond, cashew and walnut proteins are not resistant to proteolysis. Antigenicity of each of the tested tree nut proteins, under experimental conditions, was completely lost within 1 minute. Therefore resistance to in vitro proteolysis is not a prerequisite for antigenicity of almond, cashew nut, and walnut soluble proteins.
Session 46I, Toxicology & Safety Evaluation
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