UNCORRECTED PROOF /typeset2:/sco3/jobs1/ELSEVIER/saa/week.17/Psaa3166.0011 Tue May 15 14:21:27 2001 Page Tue Spectrochimica Acta Part A 000 (2001) 000–000 Review Homogeneous time resolved fluorescence resonance energy transfer using rare earth cryptates as a tool for probing molecular interactions in biology H. Bazin, M. Pre ´audat, E. Trinquet, G. Mathis * CIS Bio International, BP 84175, 30204 Bagnols sur Ce ´ze Ce ´dex, France Received 9 November 2000; received in revised form 26 February 2001; accepted 6 March 2001 Abstract An homogeneous assay technology using time resolved fluorescence and fluorescence resonance energy transfer is described. A new class of fluorescent complexes the cryptates have been used as fluorescent donor with cross-linked allophycocyanin as acceptor. This new donor/acceptor shows an exceptionally high Fo ¨ rster distance R 0 of 90 nm. This allows to build up a set of strategies to probe the interactions of biomolecules in biology, particularly for high throughput screening applications. In this article, we describe the basics of the technology and review applications developed for studying different key molecular interactions involved in cellular processes. © 2001 Elsevier Science B.V. All rights reserved. Keywords: Rare earth cryptates; Time resolved fluorescence; Fluorescence resonance energy transfer; Molecular interactions www.elsevier.nl/locate/saa 1. Introduction Most of the key mechanisms participating in cell function and regulation like receptor activa- tion, phosphorylation, transcription or gene regu- lation are based on, or involve, molecular interactions between biomolecules [1]. The recent development of techniques and knowledge from genome programs highlighted the need for under- standing encoded protein function and interac- tions, shifting the research focus from genomics to proteomics [2]. Moreover, in his search for effi- ciency, as well as for economical constrains, the pharmaceutical industry developed high through- put screening (HTS) strategies. In HTS, the goal is to screen as many compounds as possible, particularly from combinatorial chemistry, on molecular targets. This approach is leading to new technical challenges in miniaturization and au- tomation [3]. As a consequence, through years, a number of analytical techniques, labels and physicochemical * Corresponding author. Tel.: +33-466-796771; fax: +33- 466-791920. E-mail address: gmathis@cisbiointernational.fr (G. Mathis). 1386-1425/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved. PII:S1386-1425(01)00493-0