Some aspects of reactions of benzyl isothiocyanate with bovine sarcoplasmic proteins

Abstract

Benzyl-ITC (benzyl isothiocyanate) reacts preferentially with amino groups and sulfhydryl side chains of bovine sarcoplasmic proteins to form thiourea and dithiocarbamate derivatives, generally resulting in a decrease in solubility of the derivatives along a wide pH range. Under these conditions, it was also possible to show that secondary amine side chains, as found in tryptophan, also react with benzyl-ITC. A quenching of tryptophan fluorescence intensity after interaction with benzyl-ITC was also observed. Polyacrylamide gel electrophoresis (PAGE) experiments in the presence of urea indicated changes in electrophoretical mobility and in composition of subfractions. Changes in surface hydrophobicity and composition as determined by the ANS (8-anilinonaphthalene-1-sulfonate) method and RP-HPLC were also observed. Polymerisation of protein molecules after reaction with benzyl-ITC was documented using the SDS-PAGE technique. These investigations showed that a group of subfractions belonging mainly to glycolytic enzymes and associated proteins with molecular weight between 38-70 kDa was highly reactive.

Chemical Reactions of Benzyl Isothiocyanate with Myoglobin

“…As already reported previously for egg and meat sarcoplasmic proteins, the reactions between proteins and isothiocyanates led to a characteristic alteration in the solubility profile of the protein derivatives (Kroll et al 1994a; Rawel and Kroll 1995). In the reaction of myoglobin with benzyl-ITC we noted similar effects, ie a .…”

“…This phenomenon will be discussed later. A similar observation was made when we investigated the reaction of benzyl-ITC with meat sarcoplasmic proteins (Rawel and Kroll 1995). Generally, it is known that a higher ionic strength of a solvent may shift the isoelectric point in the direction of acidic pH values (Belitz and Grosch 1992).…”

“…amount of added benzyl-ITC (Kroll et a1 1994a) was not observed here. As we have shown previously, the reaction of free amino groups of egg-white proteins and meat sarcoplasmic proteins with benzyl-ITC (Kroll et a1 1994a, b;Rawel and Kroll 1995) leads to the formation of thiourea derivatives. This process is illustrated by a decrease in the amount of the free amino groups, which reflects the higher degree of derivatisation as shown for myoglobin (Table 1).…”

“…Due to their chemical structures, these sub-conditions into account, it was possible to show that stances present a very reactive group of compounds secondary amino side chains, as present in tryptophan, with strong electrophilic characteristics. We have can also react with benzyl-ITC (Rawel and Kroll 1995). already reported on the chemical reactions of various Changes in the hydrophobicity and composition of the isothiocyanates (allyl-, benzyl-, butyl-, phenyl-ITC) with proteins were also observed during the reaction of freshly cracked hen egg whites (Kroll et a1 1994a) and benzyl-ITC with bovine sarcoplasmic proteins using bovine sarcoplasmic proteins (Rawel and Kroll 1995) as RP-HPLC (Rawel and Kroll 1995).…”

“…We have can also react with benzyl-ITC (Rawel and Kroll 1995). already reported on the chemical reactions of various Changes in the hydrophobicity and composition of the isothiocyanates (allyl-, benzyl-, butyl-, phenyl-ITC) with proteins were also observed during the reaction of freshly cracked hen egg whites (Kroll et a1 1994a) and benzyl-ITC with bovine sarcoplasmic proteins using bovine sarcoplasmic proteins (Rawel and Kroll 1995) as RP-HPLC (Rawel and Kroll 1995). well as on the chemical reactions of benzyl-ITC (the This paper describes the mechanisms mentioned most reactive ITC of the ones mentioned above) with above, but focuses on the reactions between benzyl-ITC the four egg-white protein fractions : ovalbumin, conal-and epsilon amino groups of bovine myoglobin, since bumin, ovomucoid and lysozyme (Kroll et al 1994b).…”