Results (
Thai) 1:
[Copy]Copied!
Many protein allergens are glycosylated, raising the possibilitythat the glycosyl groups may contribute to their allergenicity(Jenkins et al., 1996). This is potentially relevant when consideringthe allergenicity of novel proteins for which glycosylation patternsmay differ substantially from their native counterparts. The searchfor potential N-glycosylation sites found four such sites on theCry1Ab/Ac protein but in vitro assays proved that there was noN-glycosylation site on the Cry1Ab/Ac protein actually.With the exception of pollen protein, all allergenic proteinshave high stability to digestive enzymes. Therefore this stabilitycan be used as an indicator of the potential of a protein being anallergen (Astwood, 1996). It has been reported that proteins thatare rapidly hydrolyzed to peptides and single amino acids smallerthan 3.5 kDa by pepsin can be considered less likely to be allergenic(Fu et al., 2002). And if protein allergens are to reach and passthrough the intestine mucosa to elicit an allergenic response, theymust be able to resist peptic and tryptic digestion and the acid conditionsof the digestive system. The Cry1Ab/Ac protein was degradedrapidly by digestive enzymes as assessed by both SDS–PAGE and Western Blot. These results suggest, but do not prove,that the protein has no allergenic activity, since the correlation betweenresistance to proteolysis and allergenic activity is not absolute(Fu et al., 2002).The recombinant protein was used in this paper to assess thesafety of Cry1Ab/Ac protein. The result obtained from structuraland functional equivalence assay explain that the recombinantprotein produced from E. coli was an appropriate substitute forthe extracted protein directly from genetically modified rice. Heatstability study showed the same recognition of the heat-treatedand the native proteins by anti-Cry1Ab/Ac antibodies indicatedthat the conformational changes associated with denaturationdid not affect the epitope accessibility which means that the epitopehomology search, which showed no similarities with knownallergenic epitopes, has a major weight of evidence in this safetyassessment. To have a direct assessment of the protein toxicity inmammals, an oral acute study in mice is used for evaluating thesafety of the Cry1Ab/Ac protein. In this study, the mouse acute oralLD50 was >5000 mg kg1 (body weight), which belongs to practicallynon-toxic grade. The results are coincidence with Delaneyet al. (2008) which showed the results from acute mouse toxicologystudies with proteins in GM crops were: Cry1Ab > 4000 (oral)and Cry1Ac > 4200 (oral). These results indicated that the Cry1Ab/Ac protein has no harm to human beings and animal.
Being translated, please wait..
