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Science 5 March 1971:
Vol. 171. no. 3974, pp. 901 - 903
DOI: 10.1126/science.171.3974.901
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Articles

p-Nitrophenyl Phosphate Hydrolysis and Calcium Ion Transport in Fragmented Sarcoplasmic Reticulum

Giuseppe inesi 1

1 Mellon Institute and Department of Biochemistry, Carnegie-Mellon University, Pittsburgh, Pennsylvania 15213

The calcium ion pump of fragmented sarcoplasmic reticulum can be coupled to hydrolysis of p-nitrophenyl phosphate, in the absence of added adenosine triphosphate. Comparison of the activities obtained with the two substrates suggests an analogous mechanism of transport. Independent of the substrate, a 2 : 1 ratio between calcium ion transport and substrate hydrolysis is displayed by the system, and an identical amount of work is required for ion transport against a given gradient. A phosphate ester appears necessary for substrate utilization in the pump mechanism, whereas the structure of the substrate determines the rates of activity and the affinity of the system for calcium ion.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Cloning and Expression of the Unique Ca[IMAGE]-ATPase from Flavobacterium odoratum.
W. E. Peiffer, M. G. Desrosiers, and D. R. Menick (1996)
J. Biol. Chem. 271, 5095-5100
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Science. ISSN 0036-8075 (print), 1095-9203 (online)