화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.116, No.47, 13848-13856, 2012
Robustness in Protein Folding Revealed by Thermodynamics Calculations
Long-range intraprotein interactions play important roles in protein folding. In the present study, we use two variants of the B domain of protein A (BdpA F14W/G30A and BdpA_ds) and two variants of the Trp cage (TC5b_P1 and TC5b_P2) as models to investigate how long-range hydrophobic interactions affect protein tertiary and secondary structures. The mutation of the selected residues (BdpA F14W/G30A) or the change in the sequence order of Helix1 and Helix2 (BdpA_ds) changes detailed hydrophobic interactions. However, this change does not alter the global three-helix-bundle structure of BdpA and the overall shape of the folding free-energy landscape. It does affect the formation and stability of individual secondary structures. Similarly, the addition of an extra segment to the C-terminus of Trp-cage increases the number of long-range hydrophobic interactions without making any significant change of the native structure of Trp-cage. These results show the robustness of the overall protein folding where rather large sequence changes exert significant influences on secondary but not tertiary structures.