Book of Abstracts: Albany 2003

category image Albany 2003
Conversation 13
Abstract Book
June 17-21 2003

Protein Folding by Quasi-static-like Process ? A First Order State Transition

In this study, we report that quasi-static-like processes, in which stable intermediates were introduced carefully and deliberately, may be used to reversibly unfold and refold purified native porcine growth hormone (PGH). Through circular dichroism (CD) and dynamic light scattering (DLS), we were able to study the secondary structure conformational changes, tertiary structure thermal stabilities, and the particle size distributions (PSD) of both the intermediates and the final folded product. The CD data showed that the secondary structure was restored in the initial folding stage, whereas the tertiary structure within the protein was restored one step before the last folding stage, as elucidated by thermal stability experiments. DLS analysis suggested that the average hydrodynamic radii of the folding intermediates shrunk to native-like-size immediately after the first folding stage. Our data suggested that the denaturant-containing protein folding reaction is a first-order-like state transition process. This quasi-static-like process may be useful in the prevention of occlusion or aggregate formation in protein purification and thus can be used in protein engineering to improve the overall yield from harvesting proteins.

Chia-Ching Chang1*, Ya-Chi Su2
Ming-Sung Cheng2 and
Lou-Sing Kan2,3*

Department of Physics1
National Dong Hwa University
Hualien, Taiwan 974
Department of Biochemistry1
National Chung Hsing University
Taichuang, Taiwan 403
Institute of Chemistry3
Academia Sinica, Nankang
Taipei, Taiwan 11529