Complex sentence: The process results in translated peptides or proteins that are associated with their mRNA progenitor, via a puromycin linkage, which is used, as a complex, to bind to an immobilized ligand in a selection step (affinity chromatography).
Split into simpler sentences: The process results in translated peptides or proteins that are associated with their mRNA progenitor via a puromycin linkage. The complex then binds to an immobilized target in a selection step (affinity chromatography).