Original scientific paper

The ESR Kinetic Study of Lipid Phase in HDL

Jasminka Brnjas-Kraljević ; School of Medicine, University of Zagreb, Zagreb, Croatia
Marina Kveder ; R. Bošković Institute, Zagreb, Croatia
Greta Pifat ; R. Bošković Institute, Zagreb, Croatia
Stavko Pečar ; Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
Milan Schara ; J. Stefan Institute, Ljubljana, Slovenia

Abstract

Two main high-density lipoprotein subfractions, HDL₂ and HDL₃, were spin labelled with TEMPO which partitions both in aqueous and lipid phase. The dynamics of the lipid phase was monitored ina the reduction of incorporated TEMPO with ascorbic acid. The reduction of the paramagnetic nitroxide into the nonparamagnetic hydroxilamine form decreases the ESR signal with time. The reduction curves show complex behaviour while the partition coefficients of TEMPO remain unchanged during the reaction. The reduction process in the samples containing HDL particles proceeds faster than in the aqueous solution of pure reactants, e.g. spin label and ascorbic acid. In order to explain experimental data the model for reduction of TEMPO by ascorbic acid is proposed. It assumes that the processes taking place in these heterogeneous systems are determined by the overall reaction rate, which depends on the local concentrations of the reactants, as well as on their transport properties in the particular phases.

Keywords

ESR; lipoproteins; HDL; reduction kinetics

Hrčak ID:

131784

URI

https://hrcak.srce.hr/131784

Publication date:

1.2.2001.

Visits: 1.400 *