**************** The 1st., Lab Seminar ****************************

Date: Mon, April 02, 2000  PM 1:30-

Place: No.616 Seminar room
　　　　　　 Graduate School of Information Science

Speaker: Isseki Yu

Title: Transitional-Entropy Gain of Solvent upon Protein Folding
Biophysical Journal Vol89 2005 2701-2710
Yuichi Harano and Masahiko Kinoshita
Institute of Advanced Energy,Kyoto University,Uji,Kyoto 611-0011,Japan

Abstract:
 We show that even in the complete absence of potential energies among the atoms in a protein-aqueous solution system, 
there is a physical factor that 
favors the folded state of the protein. It is a gain in the translational entropy (TE)of water originating from the 
translational movement of water 
molecules. An elaborate statistical-mechanical theory is employed to analyze the TE of water in which a protein or 
peptide with a prescribed conformation 
is immersed. It is shown that if the number of residues is sufficiently large, the TE gain is powerful enough to compete 
with the conformational-entropy 
loss upon folding. For protein G we have tested over 100 compact conformations generated by a computer simulation with 
the all-atom potentials as well as 
the native structure. A signi ?cant ?nding is that the largest TE is attained in the native structure. The translational 
movement of water molecules is 
quite effective in achieving the tight packing in the interior of a natural protein. These results are true only when the 
solvent is water whose 
molecular size is the smallest among the ordinary liquids in nature.
Biophysical Journal Volume 89 October 2005 2701 -2710 2701

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