Protein covalent modification of biologically active quinones

Abstract

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.

Hinonsko/hidrohinonski par avaron/avarol pokazuje značajnu antitumorsku aktivnost. U ovom radu proučavane su kovalentne modifikacije β-laktoglobulina avaronom, sintetičkim steroidnim hinonom 2,5(10)-estradien-1,4,17-trionom i njihovim derivatima. Tehnike za praćenje hemijske modifikacije bile su: UV/Vis spektrofotometrija, SDS PAGE i izoelektrofokusiranje. Rezultati SDS PAGE ukazuju da se dešava polimerizacija proteina.Može se videti da protein od 18 kD daje trake od 20 kD, 36 kD, 40 kD, 45 kD, 64 kD i 128 kD u zavisnosti od agensa za modifikaciju. Pomeranje pI vrednosti proteina (5,4) nakon modifikacije ka nižim vrednostima (od pI 5,0 do 5,3) pokazuje da su amino-grupe lizina glavna mesta reakcije β-laktoglobulina sa hinonima.