INTERRELATIONS OF FUNCTIONAL AND STRUCTURAL MODIFICATIONS IN SARCOPLASMIC-RETICULUM MEMBRANES AFTER LIPID PEROXIDATION

  • 1 January 1977
    • journal article
    • research article
    • Vol. 22  (4) , 625-630
Abstract
Structural and functional modifications of rabbit skeletal muscle sarcoplasmic reticulum membranes from skeletal muscles by molecular oxygen was studied. Lipid peroxidation (accumulation of 5-10 nmol hydroperoxides/mg lipids) resulted in membrane permeability increase for Ca2+ whereas the activity of Ca2+-dependent ATPase was unchanged. In the temperature range 5-30.degree. C, decrease of solubilization parameter .alpha. (for nitroxide radical 2,2,6,6-tetramethylpiperidin-1-oxyl) was registered while .alpha. reached the control values at temperatures higher than 30.degree. C. Further increase in lipoperoxide content (more than 20 nmol/mg lipids) lead to inhibition of Ca2+-dependant ATPase. In this case .alpha. was lower than in intact membranes in the whole temperature interval investigated. The loss of Ca2+-accumulating capacity was explained on the basis of peroxide clusters formation in lipid bilayer regions of sarcoplasmic membrane. One of the mechanisms of Ca2+-dependant ATPase inhibition after lipid peroxidation was the deficiency of polyunsaturated fatty acyls in microenvironment of the enzyme.

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