A rapid SNAP-tag fluorogenic probe based on an environment-sensitive fluorophore for no-wash live cell imaging.

One major limitation of labeling proteins with synthetic fluorophores is the high fluorescence background, which necessitates extensive washing steps to remove unreacted fluorophores. In this paper, we describe a novel fluorogenic probe based on an environment-sensitive fluorophore for labeling with SNAP-tag proteins. The probe exhibits dramatic fluorescence turn-on of 280-fold upon being labeled to SNAP-tag. The major advantages of our fluorogenic probe are the dramatic fluorescence turn-on, ease of synthesis, high selectivity, and rapid labeling with SNAP-tag. No-wash labeling of both intracellular and cell surface proteins was successfully achieved in living cells, and the localization of these proteins was specifically visualized.

A selective and sensitive fluorescent albumin probe for the determination of urinary albumin.

In this communication, we report a simple albumin probe based on a fluorescent molecular rotor for the detection of trace albumin levels in urine. In the presence of albumin, the probe exhibits remarkable 400-fold fluorescence enhancement with high selectivity and sensitivity. The probe was successfully applied in the quantitative detection of urinary albumin.

Fluorescence amplified detection of proteases by the catalytic activation of a semisynthetic sensor.

A general approach to mimic the sensing scheme of allosteric enzymes is developed. Through the covalent labeling of a sulfonamide inhibitor to the enzyme HCAII via SNAP-tag protein, the enzyme is rendered inactive. Catalytic activation is triggered only when a protease is present to cleave the recognized peptide sequence.