BrUSLEE
GFP with subnanosecond fluorescence lifetime

- Bright green fluorescence
- Fast maturation and enhanced photostability
- Short fluorescence lifetime (800 ps, in vitro)
- Recommended for fluorescence lifetime imaging microscopy (FLIM)

BrUSLEE (Bright Ultimately Short Lifetime Enhanced Emitter) possesses short fluorescence lifetime (800 ps) and high brightness (78% of EGFP) [Mamontova et al., 2018] Compared to other fluorescent proteins with the shortest fluorescence lifetimes reported to date mGarnet2 (760 ps) and TagRFP675 (900 ps), BrUSLEE has exceptional fluorescence brightness (QY = 0.3, EC = 86 000 M−1cm−1) Because of this unique combination îf brightness, photostability and subnanosecond fluorescence lifetime, BrUSLEE is mainly intended for fluorescence lifetime imaging microscopy. For multiparameter FLIM in green channel BrUSLEE can be used with fluorescent proteins with similar fluorescence spectra and different fluorescence lifetimes: BrUSLEE (800 ps), SLIM (1.3 ns), TagGFP2 (3.2 ns).

Main properties

BrUSLEE normalized excitation (thin line) and emission (thick line) spectra. Download BrUSLEE spectra (xls)

CHARACTERISTIC * Brightness is a product of extinction coefficient and quantum yield, divided by 1000. Molecular weight, kDa 27 Polypeptide length, aa 239 Fluorescence color green Excitation maximum, nm 487 Emission maximum, nm 509 Quantum yield 0.3 Extinction coefficient, M-1cm-1 86 000 Brightness* 26 Brightness, % of EGFP 78 Fluorescence lifetime, ps 800 Fluorescence intensity decay nearly single-exponential Aggregation no Maturation rate at 37°C fast Photostability high Cell toxicity not observed Main advantages bright green fluorescent protein with subnanosecond fluorescence lifetime

Recommended filter sets and antibodies

The protein can be recognized using Anti-Tag(CGY)FP antibody (Cat.# AB121) or Anti-GFP antibody (Cat.# AB011) available from Evrogen.

BrUSLEE can be detected using common fluorescence filter sets for EGFP, FITC and other green dyes. Recommended Omega Optical filter sets are QMAX-Green, XF100-2, XF100-3, XF115-2 and XF116-2.

Performance and use

BrUSLEE can be easily expressed and detected in a wide range of organisms. Mammalian cells transiently transfected with BrUSLEE expression vectors produce bright fluorescence in 16-18 hrs after transfection. No cytotoxic effects or visible protein aggregation are observed.

It can be used in multiparameter FLIM in green channel.

	Color-coded fluorescence lifetime imaging microscopy (FLIM) image of live HeLa cells co-expressing BrUSLEE (mitochondria), SLIM (nuclei) and TagGFP2 (cytoplasm). Color hue indicates mean lifetime at each pixel (red-orange – 750-900 ps, green – 1100-1400 ps, cyan-blue – 2700-3100 ps). Single-photon fluorescence excitation at 488 nm was used to acquire these images.

Available variants and fusions

Variant	Description	Related vector	Cat.#
Humanized BrUSLEE	BrUSLEE codon usage is optimized for high expression in mammalian cells [Haas et al., 1996], but it can be successfully expressed in many other heterological systems.	pBrUSLEE-N	FP214