Energy interconversion by the sarcoplasmic reticulum Ca2+-ATPase: ATP hydrolysis, Ca2+ transport, ATP synthesis and heat production
AUTOR(ES)
MEIS, LEOPOLDO DE
FONTE
Anais da Academia Brasileira de Ciências
DATA DE PUBLICAÇÃO
2000-09
RESUMO
The sarcoplasmic reticulum of skeletal muscle retains a membrane bound Ca2+-ATPase which is able to interconvert different forms of energy. A part of the chemical energy released during ATP hydrolysis is converted into heat and in the bibliography it is assumed that the amount of heat produced during the hydrolysis of an ATP molecule is always the same, as if the energy released during ATP cleavage were divided in two non-interchangeable parts: one would be converted into heat, and the other used for Ca2+ transport. Data obtained in our laboratory during the past three years indicate that the amount of heat released during the hydrolysis of ATP may vary between 7 and 32 Kcal/mol depending on whether or not a transmembrane Ca2+ gradient is formed across the sarcoplasmic reticulum membrane. Drugs such as heparin and dimethyl sulfoxide are able to modify the fraction of the chemical energy released during ATP hydrolysis which is used for Ca2+ transport and the fraction which is dissipated in the surrounding medium as heat.
Documentos Relacionados
- In vitro synthesis of the Ca2+ transport ATPase by ribosomes bound to sarcoplasmic reticulum membranes
- Activation of sarcoplasmic reticular Ca2+ transport ATPase by phosphorylation of an associated phosphatidylinositol.
- Ca2+ diffusion and sarcoplasmic reticulum transport both contribute to [Ca2+]i decline during Ca2+ sparks in rat ventricular myocytes.
- Crosslinking the active site of sarcoplasmic reticulum Ca(2+)-ATPase completely blocks Ca2+ release to the vesicle lumen.
- Rotational motion of the sarcoplasmic reticulum Ca2+-ATPase.