scholarly journals Effects of divalent cations and nucleotides on the reactivity of the sulfhydryl groups of sarcoplasmic reticulum membranes. Evidence for structural changes occurring during the calcium transport cycle.

1978 ◽  
Vol 253 (2) ◽  
pp. 385-389 ◽  
Author(s):  
A.J. Murphy
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Transport ◽  
Structural Changes ◽  
Divalent Cations ◽  
Sulfhydryl Groups ◽  
Transport Cycle

Equilibrium and Kinetic Studies of Calcium Transport and ATPase Activity in Sarcoplasmic Reticulum

1982 ◽  
Vol 37 (7-8) ◽  
pp. 685-691 ◽  
Author(s):  
G. Inesi ◽  
M. Kurzmack ◽  
D. Kosk-Kosicka ◽  
D. Lewis ◽  
H. Scofano ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Transport ◽  
Inorganic Phosphate ◽  
Calcium Release ◽  
Kinetic Studies ◽  
Hydrolytic Cleavage ◽  
Kinetic Measurements ◽  
Transport Cycle ◽  
Rate Limiting ◽  
Enzyme Intermediate

Abstract A number of equilibrium and kinetic measurements are presented to characterize the partial reactions of the ATPase and transport cycle in sarcoplasmic reticulum vesicles. The cycle begins with calcium and nucleotide binding on sites available on the outer surface of the vesicles. A phosphorylated enzyme intermediate is then formed, and the calcium sites are subjected to a change in their orientation and their affinity for calcium. It is shown that steps involved in calcium release on the inner side of the vesicles are rate limiting for the cycle, and are followed by hydrolytic cleavage of the intermediate with release of inorganic phosphate and recycling of the enzyme.

scholarly journals Large-scale structural changes in the sarcoplasmic reticulum ATPase appear essential for calcium transport

1990 ◽  
Vol 58 (3) ◽  
pp. 687-693 ◽  
Author(s):  
J.K. Blasie ◽  
D. Pascolini ◽  
F. Asturias ◽  
L.G. Herbette ◽  
D. Pierce ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Transport ◽  
Large Scale ◽  
Structural Changes

Functions of selected biochemical systems from the exercised-trained dog heart

1977 ◽  
Vol 42 (3) ◽  
pp. 426-431 ◽  
Author(s):  
L. A. Sordahl ◽  
G. K. Asimakis ◽  
R. T. Dowell ◽  
H. L. Stone
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Transport ◽  
Calcium Uptake ◽  
Atp Synthesis ◽  
Myocardial Cell ◽  
Ruthenium Red ◽  
Mitochondrial Membranes ◽  
Sedentary Control ◽  
Isolated Mitochondria ◽  
Biochemical Systems

Mitochondria and sarcoplasmic reticulum (SR) fractions were isolated from exercised-trained (E-T) and sedentary control dog hearts. Measurements of mitochondrial respiratory functions indicated no changes in energy-producing (ATP synthesis) capacity in mitochondria from E-T compared to control dog hearts. However, the ability of isolated mitochondria from E-T hearts to retain accumulated calcium was markedly decreased compared to controls. Inhibition of mitochondrial rates of calcium uptake with the inhibitor, ruthenium red, revealed fewer binding and/or transport sites in mitochondrial membranes from exercised-trained heart preparations. ATP-dependent binding (- oxalate) and uptake (+ oxalate) of calcium by SR preparations from E-T hearts were unchanged compared to controls. In contrast, significant differences in the rates of release of bound calcium were found in SR isolated from E-T hearts. Total myocardial protein, nucleic acids, and connective tissue levels were unchanged in E-T hearts compared to controls. The results suggest subtle changes are occurring in the energy-utilizing mechanism(s) involving calcium transport of the myocardial cell during exercise training. These changes may be related to alterations in the performance of the exercised-trained heart.

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