Interaction between 1-93 thioredoxin fragment and C-terminal 94-108 peptide.

JAVIER SANTOS; MARIO R. ERMáCORA; JOSé MARíA DELFINO

Río de Janeiro, Brasil

Workshop; Workshop on Biocalorimetry and Biological Thermodynamics; 2006

Escherichia coli thioredoxin (TRX) is a monomeric á/â protein with a fold characterized by a central â sheet surrounded by a helices. Two sub-domains are topologically noticeable, but it is unclear whether their folding occurs in a concerted fashion or not. Biophysical properties of TRX 1-93, a recombinant fragment lacking the last stretch of 15 amino acids, and TRX peptide 94-108 have been investigated in order to gain information about their folding mechanism. Complementation studies, circular dichroism, fluorescence, size exclusion chromatography and calorimetric studies (ITC) have been carried out on fragment 1-93 and peptide 94-108. The outstanding result is that the TRX 1-93 fragment, which has molten globule properties, and peptide 94-108, which has a not well defined structure, interact to form protein complex with native like properties. The association/refolding mechanism and its implications are discussed.