Characterization
of PrA-PEG-SA adaptor assembly on a solid support
and in solution. (a) Conjugation of PrA to biotin-PEG-NH2 was performed on a solid support (monomeric avidin resin) and in
solution. SDS-PAGE characterization of products reveals high purity
of mono-PEG-PrA conjugates produced via solid-phase bioconjugation,
in contrast to a heterogeneous mixture of PrA with 1, 2, 3, 4+ PEG
molecules produced by bioconjugation in solution. Molecular weight
reference is shown in kDa. (b) Conjugation of PrA-PEG-biotin to SA
on a solid support (IgG agarose) and in solution. Characterization
with hybrid gel demonstrates 1:1:1 PrA-PEG-SA stoichiometry achieved
with solid-phase procedure, whereas mixed SA conjugates with 0, 1,
2, 3+ PrA-PEG-biotin are produced via assembly in solution.