KINETIC CHARACTERISTICS OF SPONTANEOUS LIPID-PEROXIDATION IN MEMBRANES ISOLATED FROM NORMAL AND TUMOR-CELLS

Kinetic parameters of spontaneous lipid peroxidation (LP) in the endop lasmic reticulum (ER) membranes isolated from the liver of healthy mic e, tumour-host and ascitic Ehrlich tumour cells have been studied. The LP kinetics was characterized based on the primary LP products, dieni c conjugates (DC), and the extent of lipid substrate unsaturation (dou ble bond (DB) concentration per mg lipids). It was shown that the rate constants of the DC formation and DB consumption were, respectively, (6.3 +/- 0.7) . 10(-2) and(4.5 +/- 0.3) . 10(-2) min(-1) in the contro l; (2.5 +/- 0.3) . 10(-2) and (1.0 +/- 0,1) . . 10(-2) min(-1) in the ER from the tumour-host liver; (1.4 +/- 0.1) . 10(-2) and (0.38 +/- 0. 01) . 10(-2) min(-1) in the ER from the tumour cells. The initial DC a nd DB levels in membranes of the tumour cells were significantly (by 2 and 3 times) lower than in the ER isolated from the control liver. Th ere is a correlation between the DB initial level and the constants of DB consumption during LP in vitro for all the types of membranes stud ied.