Hello Abraham Abbey Paul

If you need to quench the fluorescence of GFP, you can use trypan blue as a quenching agent for green fluorescence.

Trypan blue absorbs light in the green-yellow region with a maximum absorbance wavelength around 590 nm in water. It can absorb the fluorescence emitted by green emission fluorochromes or fluorescent proteins, thus it can quench GFP.

You can refer to the references attached below for more information.

Article The effect of trypan blue treatment on autofluorescence of fixed cells

Article Discovery and Characterization of a New Cell-Penetrating Protein

I hope this will help.

Best.

What purpose?

Protease K should work, however, it is pretty aspecific and you might chop all the proteins in the mix

Malcolm Nobre Thank you so much for your answer and the attached materials. I found them handy for another aspect of my experiment(s)

Andrea Ghisleni Thank you also for your response.

I would try your suggestions.

I set out to see the controlled (preferably by enzymatic means) quenching of the protein's (GFP) fluorescence