Polyethylene glycol enhanced refolding of the recombinant human tissue transglutaminase

Tissue transglutaminase forms cross-links between lysine and glutamine side -chains of polypeptide chains in a Ca2+-dependent reaction; its structural basis is still not clarified. In this study, we demonstrate that the refold ing of the human recombinant enzyme molecule to its catalytically active fo rm from inclusion bodies needs the presence of a helper material with highe r molecular mass, but only in the initiation phase. Ca2+ and nucleotides ar e ascribed as affector molecules also in the early phase of structural reco nstitution. Two optimal concentrations of polyethylene glycol and a relativ ely long time scale for the evolution of the final structure were identifie d. The optimized refolding procedure is reported.