Linkage specific Tetra-Ub can also be used to investigate mechanism of binding and recognition by E1 or E2 enzymes, deubiquitinating enzymes, E3 ligases or other proteins that contain ubiquitin-associated domains or ubiquitin-interacting motifs (UIMs).  This product is formed with wild-type ubiquitin and linkage-specific enzymes. This product is made with wild-type human recombinant ubiquitin and linkage-specific enzymes. These chains are modified with biotin via primary amine coupling.  This results in multiple biotinylated species modified at the N-terminus, as well as lysine residues.  Biotinylated ubiquitin can be detected using avidin-linked reagents.