INTERACTIONS OF ISOTHIOCYANATES WITH EGG-WHITE PROTEINS

Glucosinolates and their very highly reactive breakdown products (main ly isothiocyanates = ITC) belong to one of the most important natural toxicants. This paper deals with the interactions of allyl-, butyl-, p henyl- and benzyl ITC with egg white proteins resulting in the formati on of ITC-protein-conjugates. The ITC's react with amino groups by for ming thiourea derivatives. Such reactions are well described by change s in the amounts of free amino groups and available lysine. Further re action sites am sulphhydryl side chains of proteins leading to dithioc arbamate esters. The investigations further show that such reactions a re accompanied with a decrease in the solubility of the prepared conju gates. Simultaneously a shift of the isoelectric range to a lower valu e of pH can also be observed. Changes in electrophoretic patterns and mobility can also be seen due to the strong electrophilic attack of IT C to proteins. Comparison of the 4 investigated preparations shows tha t benzyl-ITC is the most reactive partner for egg white proteins.