Fig. 5.

Comparison of thioester protein functionalization for biotin–PEG₄–hydrazide and biotin–PEG₃–aminoxy. (A) Chemical structures of biotin–PEG₄–hydrazide (top) and biotin–PEG₃–aminoxy (bottom). (B) PEG-plasma was incubated with biotin–PEG₄–hydrazide, biotin–PEG₃–aminoxy. Biotinylated proteins were captured with SA-resin, eluted by boiling in SDS loading buffer and visualised by 6% SDS-PAGE and Coomassie staining. Total protein present in reaction mix pre-SA capture (left 3 lanes) is shown beside the pull-down proteins (right three lanes).