Biarsenical

F4FlAsH-P12 61 at 544 nm expanded the spectral range of the biarsenical dyes. Furthermore, the fluorescence lifetime increased to a value of 5.2 ns. Owing to the results of this study, the authors suggested that the two compounds (57 and 58) would form an excellent FRET pair with a large critical distance. In addition, they envisage that the observed characteristics should facilitate improved structural and dynamic studies of proteins in living cells. 

Due to the fact that biarsenical-TC complex is stable under the denaturing conditions typically used for gel electrophoresis of proteins and has a molecular weight of less than 2 KDa, when bonded to the biarsenical dye [157], Kottegoda and collaborators [161] studied the biarsenical dyes, as fluorescent probes for in vitro, cellular peptide, and proteins studies using capillary electrophoresis. 

Hearps AC, Pryor MJ, Kuusisto HV et al (2007) The biarsenical dye Lumio exhibits a reduced ability to specifically detect tetracysteine-containing proteins within live cells. J Fluoresc 17 593-597... 

Adams SR, Campbell RE, Gross LA et al (2002) New Biarsenical ligands and tetracysteine motifs for protein labeling in vitro and in vivo synthesis and biological applications. J Am Chem Soc 124 6063-6076... 

Spagnuolo CC, Vermeij RJ, Jares-Erijman EA (2006) Improved Photostable FRET-compe-tent biarsenical—tetracysteine probes based on fluorinated fluoresceins. J Am Chem Soc 128 12040-12041... 

Martin BR, Giepmans BNG, Adams SR, Tsien RY (2005) Mammalian cell—based optimization of the biarsenical-binding tetracysteine motif for improved fluorescence and affinity. Nat Biotechnol 23 1308-1314... 

Kottegoda S, Aoto PC, Sims CE, Allbritton NL (2008) Biarsenical—tetracysteine motif as a fluorescent tag for detection in capillary electrophoresis. Anal Chem 80 5358-5366... 

Of increasing utility have been the tetracysteine tags specific for fluorogenic, biarsenical ligands (e.g., FlAsH, Table 12.2, Fig. 12.3, method 11 [72, 113, 114]). The latter bind with high affinity and selectivity to very short peptide sequences incorporating two dicysteine elements separated by 2 or more residues. The variety of dyes... 

Fig. 12.3. Some expression systems involving noncovalent (binding) linkages. Numbers correspond to entries (methods) in Table 12.2 (5) labeling with methotrexate derivatives that recognize a dihydrofolatereductase segment, and (11) labeling with biarsenical derivatives binding to a 6-12 tetracysteine...

FRET parameters (J, Ro) for various biarsenical reagents. Taken from [120]... 

Cao, H., Chen, B., Squier, T. C. and Uljana Mayer, M. U. (2006). CrAsH A biarsenical multi-use affinity probe with low non-specific fluorescence. Chem. Comm. 2601-3. 

Spagnuolo, C. C., Vermeij, R. J. and Jares-Erijman, E. A. (2006). Improved photostable FRET-competent biarsenical-tetracysteine probes based on fluorinated flluoresceins. J. Am. Chem. Soc. 128, 12040-3041. 

The Biarsenical-tetracysteine Protein Tag Chemistry and Biological Applications... 

The biarsenical-tetracysteine method was first introduced more than 7 years ago, and further refinements and development of novel applications are still appearing. Within the last few years, biologists have started to exploit the unique features of this system for probing protein trafficking, turnover, localization, and dynamics. This review aims to describe the conception and development of this protein tag and its applications in the biological sciences. 

Fig. 8.1-1 A comparison of the relative sizes of CFP and the biarsenical-tetracysteine complex. The atoms comprising the chromophores are shown in color with the peptide backbone depicted in green.

History and Design Concepts of the Tetracysteine-biarsenical System... 

Biarsenical derivatives of other fluorophores emitting at longer wavelengths would also be useful, particularly those based on nonxanthene skeletons... 

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