NMR-STUDY OF THE RECONSTITUTION OF THE BETA-SHEET OF THIOREDOXIN BY FRAGMENT COMPLEMENTATION

The study of complementary protein fragments is thought to be generall y useful to identify early folding intermediates. A prerequisite for t hese studies is the reconstitution of the native-like structure by fra gment complementation. Structural analysis of the complementation of t he domain-sized proteolytic fragments of E. coli thioredoxin, using a combination of H-exchange and 2D NMR experiments as a fingerprint tech nique, provide evidence for the extensive reconstitution of a native b eta-sheet, with local conformational adjustments near the cleavage sit e. Remarkably, the antiparallel beta-strand between the fragments show s a native-like protection of the amide protons to solvent exchange. O ur results indicate that these fragments can be useful to study the ea rly events in the still little understood formation of beta-sheets. (C ) 1995 Wiley-Liss, Inc.