engleski

Interaction of caffeine with human plasma low density lipoproteins

Human plasma low density lipoproteins (LDLs) are supramolecular lipid-protein assemblies involved in the cholesterol transport in the bloodstream and are believed to be directly involved in the developement of atherosclerosis. They exhibit structural complexity with the surface monolayer organization of phospholipids surrounding the hydrophobic core. Their structure at atomic resolution has not yet been elucidated. Caffeine is ubiquously present in everyday diet among most people. It is completely absorbed from the intestine into the bloodstream, where there is a possibility for it to interact with plasma macromolecules. In this contribution we present the analysis of caffeine interaction with LDL. In order to elucidate the mechanism of caffeine binding to LDL, UV/VIS absorbtion spectroscopy was employed. Caffeine titration of LDL was performed by varying ionic strenght, pH and temperature. Conformational changes during caffeine binding were monitored by intrinsic fluorescence quenching and electron paramagnetic resonance (EPR) spectroscopy. Susceptibility to copper induced oxidation was probed for native LDL and LDL interacting with physiologically relevant amounts of caffeine. The results indicate that the caffeine binding to LDL changes upon varying the solution conditions. Although caffeine does not affect the lenght of the lag phase of the LDL copper induced oxidation, it changes the properties of the apolipoprotein B100 (apoB) of the LDL particle during the lag phase. According to the results, the nature of the interactions has been proposed and the spectroscopic properties of the complex have been described.

LDL; caffeine; binding; oxidation

nije evidentirano