J. Kroll et H. Rawel, CHEMICAL-REACTIONS OF BENZYL ISOTHIOCYANATE WITH MYOGLOBIN, Journal of the Science of Food and Agriculture, 72(3), 1996, pp. 376-384
The interaction of benzyl isothiocyanate (in concentrations of 2 . 5-2
50 mg benzyl-ITC g(-1) protein) with myoglobin leads to the formation
of derivatives which have been characterised in terms of their solubil
ity, free epsilon amino groups, content of tryptophan and its quenchin
g as well as their molecular properties determined with electrophoreti
c and chromatographic methods. The reaction takes place primarily at t
he epsilon amino groups of lysine, whose content decreases depending o
n the concentration of the benzyl-ITC present. A second possibility is
the reaction of the secondary amino group present in tryptophan, whos
e concentration also decreases. These reactions increased the electrop
horetical mobility during PAGE in the presence of urea, as a result of
which the isoelectric points shifted from 7 . 33-7 . 45 to 5 . 13-5 .
6 as shown by means of the isoelectrical focusing technique. The mole
cule size (size exclusion chromatography) decreased as a result of inc
reased hydrophobicity (RP-HPLC). A slight polymerisation with an incre
ase in the content of dimer (38 kDa, SDS-PAGE) was observed. The deriv
ative with the highest degree of derivatisation (250 mg benzyl-ITC g(-
1) protein) showed an unexpected behaviour with all its investigated p
roperties, which can be explained as a result of structural changes ta
king place during the process of derivatisation.