[Structural-functional state of Ca-transport system of sarcoplasmic reticulum membranes after deep freezing].
The structure and functions of the Ca-transport system of sarcoplasmic reticulum (SR) at low temperatures (-5--196 degrees) were studied. It was shown that during SR freezing-thawing the activation energy of ATP enzymatic hydrolysis as well as the Ca-ATPase sensitivity to calcium ions were changed. The Km value for the carrier seemed to be unaffected thereby. Using the EPR method it was shown that after freezing down to -196 degrees and a subsequent thawing the protein-lipil interactions and the orderliness of phospholipid fatty acid chains in the SR membranes were altered. On the contrary, the activity of Ca-ATPase isolated from SR membranes remained unchanged, which is indicative of the enzyme resistance to the cold. The mechanisms responsible for the impairment of the functioning of Ca-transport system of SR membranes due to freezing are discussed.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D004789:Enzyme Activation; D005615:Freezing; D007473:Ion Channels / Q000378:metabolism*; D007700:Kinetics; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013816:Thermodynamics
D007473:Ion Channels; D000252:Calcium-Transporting ATPases; D002118:Calcium
Strukturno-funktsional'noe sostoianie Ca-transportiuruiushcheĭ sistemy membran sarkoplazmaticheskogo retikuluma posle zamorazhivaniia.