FIGURE 5:

moxGFP2 is a stably folded and photostable oxidation-resistant GFP. (A) Fluorescence of mEGFP, msGFP2, and various msGFP2 mutants when expressed in E. coli as fusions to proinsulin. Mean cellular fluorescence is shown in arbitrary units (a.u.), together with SEM values based on nine replicates per sample (three replicates from each of three different colonies). (B) Spectra of moxGFP2 and EGFP. Purified GFPs were diluted to an absorbance at 280 nm of ∼0.1. Excitation spectra were collected for emission at 507 nm, and emission spectra were collected for excitation at 488 nm. The spectra were normalized to the highest values. (C) Photobleaching of purified GFP variants. moxGFP2 and EGFP were imaged repeatedly by widefield microscopy. Images were collected every 0.1 s, and the emission signals were quantified. Each curve was normalized to the emission signal from the first image.