For lysing, cells were centrifuged at 100 rpm for 5 minutes and the supernatant decanted off. To remaining cells was added 200 µL of 200 mM ammonium acetate; the suspension was vortexed and centrifuged again at 100 rpm for 5 minutes. This was repeated three times. After a final suspension in ammonium acetate, the cells were frozen at -80°C and thawed three times to afford an aqueous solution of cell lysate. mNeongreen protein purification pOPINO-mNeonGreen-His plasmid were expressed in EColi strain BL21 by growing cultures in TB medium supplemented with 100 ug/ml ampicillin and 0.1% Glucose overnight at 27 °C and shaking at 200 rpm. mNeongreen-His was purified by Niaffinity chromatography as previously described by Bird et al . mNeongreen were eluted in PBS buffer pH 7.4 containing 300mM imidazole and stored in -80 °C until further use.