Figure 4.
Purification and characterization of P22-GFP Sortase fusion product by cesium chloride and dialysis approaches. (A) Side by side comparison of results from cesium chloride purification of P22-LPETG VLPs without sortase added (left) and with sortase added (right) to the ligation reaction mixture. For the reaction containing sortase, a noticeable solid “disk” was observed (arrow pointing to zoomed in view) with a greenish hue. (B) SDS-PAGE was run on a sample of the disk and the gel shows that the disk is composed of cross-linked P22-GFP. (C) TEM images taken of the disk indicate that it is composed of P22 VLPs. (D) Solid “disks” were collected and evaluated by SAXS, but showed no long-range organization beyond the unaltered P22-LPETG. (E) Dialysis results for free polyG-GFP (left) and sortase ligation reaction mixtures (right) with 50 kDa MWCO and 100 kDa MWCO dialysis tubing, respectively. (F) SDS-PAGE gel evaluation of dialysis samples with lanes: (1) ladder, (2) GFP 50 MWCO dialysis, (3) GFP 100 kDa MWCO, (4) P22/GFP ligation reaction 50 kDa MWCO, and (5) P22/GFP ligation reaction 100 kDa MWCO. Larger MWCO allowed removal of free GFP.