K33-Linked Di-Ubiquitin

K33-linked di-ubiquitin (Ub2) is a diubiquitin linked by a native isopeptide bond between the C-terminal glycine of the distal ubiquitin and the epsilon amino group of lysine 33 on the proximal ubiquitin. The product is generated using chemical ligation. It is a useful substrate for identifying and characterizing deubiquitinating enzymes that cleave the K33 linkage and for structural and binding studies of ubiquitin chain recognition by ubiquitin-associated domains (UBA) or ubiquitin-interacting motifs (UIMs).