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Title: Effect of temperature on the reversal of the calcium ion pump in sarcoplasmic reticulum
Authors: Vale, M. G. P. 
Carvalho, A. P. 
Issue Date: 15-Feb-1980
Publisher: Portland Press
Citation: Biochemical Journal. 186:2 (1980) 461-467
Serial title, monograph or event: Biochemical Journal
Issue: 186:2
Abstract: Sarcoplasmic-reticulum vesicles were actively loaded with Ca2+ in the presence of phosphate, and the ADP-induced Ca2+ efflux and ATP synthesis were measured as a function of temperature. Arrhenius plots show break points for both processes at about 18 and 37 degrees C. Between 18 and 37 degrees C, Ca2+ efflux and ATP synthesis occur with an activation energy of 67.2-71.4 kJ/mol, whereas it is about 189-210 kJ/mol for temperatures below 18 degrees C. Above 37 degrees C, the rates of ADP-induced Ca2+ release and of ATP synthesis sharply decline until the temperature reaches about 42 degrees C. Above this temperature, the Ca2+ efflux increases again even in absence of ADP, although the synthesis of ATP is inhibited, which reflects leakiness of the vesicles. The results show that the transition temperatures for ADP-induced Ca2+ efflux and for ATP synthesis resemble those for active Ca2+ uptake, which indicates that the same coupling mechanism is involved during the inward and outward Ca2+ translocations across the membrane
Description: Biochemical Journal. 186:2 (1980) 461-467
ISSN: 0306-3283
DOI: 10.1042/bj1860461
Rights: openAccess
Appears in Collections:FCTUC Ciências da Vida - Artigos em Revistas Internacionais

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