Toxicological evaluation of proteins introduced into food crops

Abstract

This manuscript focuses on the toxicological evaluation of proteins introduced into GM crops to impart desired traits. In many cases, introduced proteins can be shown to have a history of safe use. Where modifications have been made to proteins, experience has shown that it is highly unlikely that modification of amino acid sequences can make a non-toxic protein toxic. Moreover, if the modified protein still retains its biological function, and this function is found in related proteins that have a history of safe use (HOSU) in food, and the exposure level is similar to functionally related proteins, then the modified protein could also be considered to be “as-safe-as” those that have a HOSU. Within nature, there can be considerable evolutionary changes in the amino acid sequence of proteins within the same family, yet these proteins share the same biological function. In general, food crops such as maize, soy, rice, canola etc. are subjected to a variety of processing conditions to generate different food products. Processing conditions such as cooking, modification of pH conditions, and mechanical shearing can often denature proteins in these crops resulting in a loss of functional activity. These same processing conditions can also markedly lower human dietary exposure to (functionally active) proteins. Safety testing of an introduced protein could be indicated if its biological function was not adequately characterized and/or it was shown to be structurally/functionally related to proteins that are known to be toxic to mammals.
Keywords: Food processing, food safety, genetically modified crops, history of safe use, threshold of toxicological concern

History of safe use
   Relevance of HOSU concept to protein safety assessment
   Structural/functional relatedness – lessons from protein engineering
   Bioinformatics and HOSU
Dietary exposure: impact of food processing on introduced proteins
   Influence of structure on protein function
   Alteration of protein structure triggered by changes in the microenvironment
   Testing for denaturation by heat treatment
Application of threshold of toxicological concern for proteins
Potential interactions between introduced proteins in combined-trait crops
Lack of scientific justification to test proteins for genotoxic potential

Crit Rev Toxicol. Nov 2013; 43(Suppl 2): 25–42.
Published online Oct 25, 2013. doi: 10.3109/10408444.2013.842956
PMCID: PMC3835160

Toxicological evaluation of proteins introduced into food crops
Bruce Hammond, 1 John Kough, 2 Corinne Herouet-Guicheney, 3 and Joseph M. Jez 4 *, on behalf of the ILSI International Food Biotechnology Committee Task Force on the Use of Mammalian Toxicology Studies in the Safety Assessment of GM Foods

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