36B-19 |
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A. O. Ofori-Anti1, E. O. SAKYI-DAWSON1, K. M. Bosompem2, L. L. Murdock3, T. J. V. Higgins4, and S. S. Nielsen5. (1) Dept. of Nutrition & Food Science, Univ. of Ghana, PO Box LG-134, Legon, Ghana, (2) Noguchi Memorial Institute for Medical Research, Univ. of Ghana, PO Box LG-025, Legon, Ghana, (3) Dept. of Entomology, Purdue Univ., 901 W. State St., 124 Whistler Hall of Agricultural Research, West Lafayette, IN 47907-2089, (4) Plant Industry, Commonwealth Scientific & Industrial Research Org., GPO Box 1600, Canberra, 2601, Australia, (5) Dept. of Food Science, Purdue Univ., 745 Agricultural Mall Dr., West Lafayette, IN 47907 Insect resistance of legumes prone to destruction by Callosobruchus maculatus may be improved by genetically engineering them to produce α-amylase inhibitor (AAI) commonly found in common beans (Phaseolus vulgaris). Transgenic foods modified to produce novel proteins have to be tested for allergenicity potential, especially if the gene source is from a commonly allergenic food. Analyses of physical and chemical properties of known food allergens show that most resist heat inactivation and degradation by digestive enzymes among other characteristics. This study set out to investigate the effect of heat and digestive enzymes on AAI from Pinto Bean and Tendergreen bean (varieties of Phaseolus vulgaris) and AAI from transgenic Chickpea, and transgenic Garden peas (both expressing AAI from Tendergreen bean). Crude and purified extracts of the recombinant and non-recombinant AAI were heated at 99.9oC and samples analysed at timed intervals for AAI activity by iodometry and immunogenicity by Dot ELISA. Heated and unheated extracts were subjected to action of mammalian enzymes in vitro and the extent of digestion monitored by Dot ELISA and Western Immunoblotting. There was loss in AAI activity in less than 10 minutes of heating but no reduction in the ability of the heated AAI to elicit immune response. The heat-denatured recombinant and non-recombinant AAI were both highly susceptible to digestion, with complete loss of immunogenicity. However, the unheated AAI from the different legumes exhibited varying degrees of resistance to digestion. The relative susceptibility of the recombinant AAI to thermal inactivation and hydrolysis by digestive enzymes is a desirable trait that is not common to most food allergens. This provides some modest basis, subject to further investigations, to postulate that transgenic legumes expressing the AAI from Tendergreen may not present problems with allergenicity.
Session 36B, Biotechnology: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |