doiSerbia

Protein covalent modification of biologically active quinones

Sladić Dušan M. (Faculty of Chemistry, Belgrade)
Novaković Irena (Institute for Chemistry, Technology and Metallurgy, Department of Chemistry, Belgrade, Serbia and Montenegro)
Vujčić Zoran M. (Faculty of Chemistry, Belgrade)
Božić Tatjana T. (Faculty of Chemistry, Belgrade)
Božić Nataša M. (Institute for Chemistry, Technology and Metallurgy, Department of Chemistry, Belgrade, Serbia and Montenegro)
Milić Dragan (Faculty of Chemistry, Belgrade)
Šolaja Bogdan A. (Faculty of Chemistry, Belgrade)
Gašić Miroslav J. (Faculty of Chemistry, Belgrade and Institute for Chemistry, Technology and Metallurgy, Department of Chemistry, Belgrade, Serbia and Montenegro)

The avarone/avarol quinone/hydroquinone couple shows considerable antitumor activity. In this work, covalent modification of β-lactoglobulin by avarone and its derivatives as well as by the synthetic steroidal quinone 2,5(10)-estradiene- 1,4,17-trione and its derivatives were studied. The techniques for studying chemical modification of β-lactoglobulin by quinones were: UV/Vis spectrophotometry, SDS PAGE and isoelectrofocusing. SDS PAGE results suggest that polymerization of the protein occurs. It could be seen that the protein of 18 kD gives the bands of 20 kD, 36 kD, 40 kD, 45 kD, 64 kD and 128 kD depending on modification agent. The shift of the pI of the protein (5.4) upon modification toward lower values (from pI 5.0 to 5.3) indicated that lysine amino groups are the principal site of the reaction of β-lactoglobulin with the quinones.

Keywords: quinone, avarone, steroidal quinones, β-lactoglobulin, covalent modification