Labeling of the peptide with fluorophores during solid phase peptide synthesis (SPPS) has many advantages, but one drawback of this method is the final deprotection/cleavage from the resin with concentrated trifluoroacetic acid (TFA), which can cause fluorophore degradation and as result in fluorescent properties lost:
TFA cleavage from a solid resin as a final step in SPPS
Non-sulfonated Cyanine dyes showed to be tolerant towards strong acids like TFA (Lee et al., 2008), but there is not enough information about sulfonated Cyanine dyes' stability in strong acids.
To address this problem, our product #x7390 - Sulfo-Cyanine5.5 Carboxylic acid (batch #NFD5H) was treated with concentrated TFA for 2 hours and then characterized by LC-MS, UV-VIS absorption spectrum also was measured to show the spectral properties intact and compared with the same quality control data measured for the same product before treatment with TFA.
Sulfo-Cyanine5.5 carboxylic acid before TFA treatment
Sulfo-Cyanine5.5 carboxylic acid after TFA treatment
