[Mechanism of tocopherol stabilization of sarcoplasmic reticulum Ca2+-ATPase from thermodenaturation activated by fatty acids].
The stabilizing effect of alpha-tocopherol on the enzymatic system of Ca2+ transport in sarcoplasmic reticulum (SR) membranes of rabbit skeletal muscle was studied. Exogenous fatty acids (e. g. arachidonic) cause destabilization of the enzymatic Ca2+ transport system by decreasing the thermal stability of Ca2+-dependent ATPase and the Ca2+-transport ability (Ca/ATP ratio) of SR membranes. Incorporation of alpha-tocopherol into SR membranes increases the thermal stability of the enzymatic Ca2+ transport system exposed to the damaging action of free fatty acids. Using differential scanning microcalorimetry, it was shown that arachidonic acid causes a shift of the maximum on the curve for the temperature dependence of specific thermal capacity of SR membranes towards the low temperature region. Under a combined action of arachidonic acid and alpha-tocopherol the position of the maxima on the temperature dependence curve for specific thermal capacity of SR membranes is close to the control value. A quantitative estimation of the values of molar enthalpies for SR membrane thermodenaturation demonstrated that the melting of Ca2+-dependent ATPase, the main intrinsic protein of SR membranes, is biphasic. The data obtained are discussed in terms of hypothetical mechanisms of protection of the enzymatic Ca2+ transport system against the damaging action of free fatty acids.
D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology; D001692:Biological Transport; D002135:Calcium-Binding Proteins / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D005227:Fatty Acids / Q000494:pharmacology*; D006358:Hot Temperature; D011489:Protein Denaturation / Q000187:drug effects; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D014810:Vitamin E / Q000494:pharmacology*
D001095:Arachidonic Acids; D002135:Calcium-Binding Proteins; D005227:Fatty Acids; D014810:Vitamin E; D016718:Arachidonic Acid; D000252:Calcium-Transporting ATPases
Mekhanizm stabilizatsii tokoferolom Ca2+-ATPazy sarkoplazmaticheskogo retikuluma ot termodenaturatsii, aktiviruemoĭ zhirnymi kislotami.