Light-Triggered and Light-Dependent Atpase Activities in Chloroplasts

C. Carmeli, M. Avron

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12 Scopus citations


This chapter discusses the activities of light-triggered and light-dependent adenosine triphosphatase (ATPase) in chloroplasts. Chloroplasts prepared from leaves of plants such as lettuce or spinach catalyzes the hydrolysis of adenosine triphosphate (ATP) to adenosine diphosphate (ADP) and Pi at very low rates. However, in the presence of sulfhydryl reagents, such as cysteine, lipoic acid, or dithiothreitol, light triggers an ATPase activity in chloroplasts. This light-triggered and magnesium-dependent ATPase activity is maintained in the dark after light-triggering. Light also induces a calcium-activated, light-dependent ATPase activity which ceases as soon as the light is turned off. Both the light-triggered and the light-dependent ATPase activities represent a reversal of some of the reactions involved in the latter stages of photophosphorylation. ATPase activity is assayed either by a colorimetric determination of the Pi released from ATP or by the more sensitive determination of [32P] Pi released from [32P] ATP.

Original languageEnglish
Pages (from-to)92-96
Number of pages5
JournalMethods in Enzymology
Issue numberC
StatePublished - 1 Jan 1972


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