A novel cycling assay for cellular cADP-ribose with nanomolar sensitivity

Richard Graeff, Hon Cheung Lee

Research output: Contribution to journalArticle

140 Scopus citations

Abstract

cADP-ribose (cADPR) is a novel cyclic nucleotide derived from NAD that has now been established as a general Ca2+ messenger in a wide variety of cells. Despite the obvious importance of monitoring its cellular levels under various physiological conditions, its measurement has been technically difficult and requires specialized reagents. In this study a widely applicable high-sensitivity assay for cADPR is described. ADP-ribosyl cyclase normally catalyses the synthesis of cADPR from NAD+, but the reaction can be reversed in the presence of high concentrations of nicotinamide, producing NAD+ from cADPR stoichiometrically. The resultant NAD+ can then be coupled to a cycling assay involving alcohol dehydrogenase and diaphorase. Each time NAD+ cycles through these coupled reactions, a molecule of highly fluorescent resorufin is generated. The reaction can be conducted for hours, resulting in more than a thousand-fold amplification of cADPR. Concentrations of cADPR in the nanomolar range can be measured routinely. The unique ability of ADP-ribosyl cyclase to catalyse the reverse reaction provides the required specificity. Using this assay, it is demonstrated that cADPR is present in all tissues tested and that the levels measured are directly comparable with those obtained using a radioimmunoassay. All the necessary reagents are widely available and the assay can be performed using a multiwell fluorescence plate reader, providing a high-throughput method for monitoring cADPR levels. This assay should be valuable in elucidating the messenger role of cADPR in cells.

Original languageEnglish (US)
Pages (from-to)379-384
Number of pages6
JournalBiochemical Journal
Volume361
Issue number2
DOIs
StatePublished - Jan 15 2002

Keywords

  • ADP-ribosyl cyclase
  • CD38
  • Ca signallin
  • NAD
  • NADH

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