Efficient Generation of Hydrazides in Proteins by RadA Split Intein

Hydrazides at proteins' C termini are much desired because of their straightforward use for bioconjugations and chemical modifications. However, traditional preparation methods often lack the necessary biocompatibility. In their full paper, J. Liu, S. Rozovsky, et al. show that combining thiols and hydrazine under mild conditions results in the high-yield generation of such C-terminal hydrazides. The addition of thiols not only accelerates the formation of the transient thioester intermediate, and the subsequent hydrazinolysis that promotes hydrazide formation at proteins' C terminus, but also alleviates the problem of destructive protein aggregation. Employing split inteins to trigger hydrazinolysis provides an additional level of control of this now biocompatible generation method.