Recombinant Tβ4 folding and characterization by synchrotron radiation circular dichroism spectroscopy
Yung-Chin Huang1*, Hsueh-Liang Chu1, Peng-Jen Chen1, Chia-Ching Chang1,2
1Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan
2Institute of Physics, Academia Sinica, Nankang, Taiwan
* presenting author:Yung-Chin Huang,
Thymosin beta 4 (Tβ4) is a ubiquitous peptide containing 43-amino acid, has been demonstrated that it can promote angiogenesis, cell migration, tissue development and cardiac protection. Tβ4 is multifunctional protein and has been proposed as an intrinsically disordered protein. Due to the rapid degradation property of Tβ4, it is the difficult to reveal its folding mechanism. However, we found that the recombinant Tβ4 protein (rTβ4), which as a fusion protein, is relatively stable and maintains identical function of Tβ4. Therefore, rTβ4 can be used as a model to study its folding mechanism. By using over-critical folding process, the stable folding intermediates of rTβ4 can be obtained. Secondary structures of folding intermediates which analyzing by synchrotron radiation circular dichroism (SRCD) spectra indicate that rTβ4 is a random coli major protein. Moreover, the conformation and hydrophobic region becomes compact gradually was characterized by fluorescence spectroscopies. Thermal stability analyzed by differential scanning calorimetry indicates that rTβ4 lacks stable tertiary structure. These results indicate that rTβ4 is an intrinsically disordered protein.

Keywords: Synchrotron radiation circular dichroism (SRCD), Thymosin beta 4 (Tβ4), Disordered protein, Thermal stability