[Interaction of alkali metal ions with Ca2+-binding center of Ca2+- ATPase of the sarcoplasmic reticulum in skeletal muscles].
Sodium ion interaction with sarcoplasmic reticulum (SR) membranes leads to considerable alterations of the [23Na]NMR lineshape. Na+ binding to SR in the presence of Ca2+ and H+ is well described by a model which postulates a competitive ion binding to high and low affinity sites of Ca2+-ATPase. The dissociation constant, Kd, for high and low affinity sites is 5 and 10 mM, respectively, for Na+ and (3-5).10(-8) and 1.5.10(-3) M, respectively, for Ca2+. The pK value for high and low affinity sites is 7.3 and 6.1, respectively. Other alkaline metal ions compete with Na+ for the low affinity sites of Ca2+-ATPase; their affinities decrease in the following order: Na+ = K+ greater than Rb+ greater than Cs greater than Li+. Some of the Na+ binding sites (approximately 10%) do not interact with Ca2+.
Timonin
I M
IM
Dvoriantsev
S N
SN
Petrov
V V
VV
Ruuge
E K
EK
Levitskiĭ
D O
DO
D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism; D008672:Metals, Alkali / Q000378:metabolism*; D009132:Muscles / Q000201:enzymology*; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D012964:Sodium / Q000378:metabolism
D008672:Metals, Alkali; D006859:Hydrogen; D012964:Sodium; D000252:Calcium-Transporting ATPases; D002118:Calcium
Vzaimodeĭstvie ionov shchelochnykh metallov c Ca2+- sviazyvaiushchimi tsentrami Ca2+-ATPazy sarkoplazmaticheskogo retikuluma skeletnykh myshts.