The ligation of peptide hydrazides at a Gly site carrying a removal auxiliary was found to be an efficient process. This technology was successfully used for the synthesis of ubiquitin C-terminal conjugates. Recombinant Ub(1-75)-NHNH2 was prepared through the hydrozinolysis of the Ub(1-75)-intein fusion protein. It was ligated with a glycine derivative modified with an acid-sensitive thiol auxiliary. The final acid treatment produced the desired bioactive ubiquitin conjugates in practical quantities. Thus, the method described here extends the protocols of expressed protein ligation.
Keywords: deubiquitinating enzymes; expressed protein ligation; native chemical ligation; peptide hydrazides; ubiquitin.
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