Comparison List


a.k.a. SPOntaneous switching ON fluorescent protein

SPOON is a photoswitchable green/yellow fluorescent protein published in 2018, derived from Aequorea victoria. It has high acid sensitivity.
Oligomerization Organism Molecular Weight Cofactor
Monomer Aequorea victoria 26.8 kDa -



State Ex λ Em λ EC (M-1 cm-1) QY Brightness pKa Maturation (min) Lifetime (ns)
on 510 527 54,000 0.5 27.0 7.2 112.0  


From To Switch λ
off on 339
on off 411


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SPOON Sequence

SPOON was derived from Dreiklang with the following mutations: I47V/T59S/M153T/S208G/M233T
amino acid numbers relative to avGFP. show relative to Dreiklang

GenBank: LC320161


Dreiklang can switch on spontaneously by thermal relaxation that is caused by a dehydration of chromophore, which enables a simpler single molecule localization-based microscopy, called DSSM (decoupled stochastic switching microscopy)... Compared to GSDIM, DSSM enables super-resolution imaging at relatively lower power density illumination for switching-off (0.2 kW cm–2 by 405 nm light, while GSDIM required 3 kW cm–2). However, DSSM still requires 405 nm illumination to make Dreiklang adopt the fluorescent off state. To overcome this problem, we developed an improved PSFP (SPOON) that has a fast blinking behavior due to thermal switching-on and rapid photoswitching-off with the same 488 nm excitation light needed for fluorescent emission.

Arai et al. (2018)

Primary Reference

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