Volume 77, Issue 4 pp. 950-961
Research Article

Free-energy function based on an all-atom model for proteins

Takashi Yoshidome

Takashi Yoshidome

Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan

Search for more papers by this author
Koji Oda

Koji Oda

Taisho Pharmaceutical Co., Ltd., Yoshino-cho, Kita-ku, Saitama 331-9530, Japan

Search for more papers by this author
Yuichi Harano

Yuichi Harano

Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan

Search for more papers by this author
Roland Roth

Roland Roth

Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, D-70569 Stuttgart, Germany

ITAP, Universität Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany

Search for more papers by this author
Yuji Sugita

Yuji Sugita

RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan

Search for more papers by this author
Mitsunori Ikeguchi

Mitsunori Ikeguchi

International Graduate School of Arts and Sciences, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan

Search for more papers by this author
Masahiro Kinoshita

Corresponding Author

Masahiro Kinoshita

Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan

Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan===Search for more papers by this author
First published: 06 July 2009
Citations: 32

Abstract

We have developed a free-energy function based on an all-atom model for proteins. It comprises two components, the hydration entropy (HE) and the total dehydration penalty (TDP). Upon a transition to a more compact structure, the number of accessible configurations arising from the translational displacement of water molecules in the system increases, leading to a water-entropy gain. To fully account for this effect, the HE is calculated using a statistical-mechanical theory applied to a molecular model for water. The TDP corresponds to the sum of the hydration energy and the protein intramolecular energy when a fully extended structure, which possesses the maximum number of hydrogen bonds with water molecules and no intramolecular hydrogen bonds, is chosen as the standard one. When a donor and an acceptor (e.g., N and O, respectively) are buried in the interior after the break of hydrogen bonds with water molecules, if they form an intramolecular hydrogen bond, no penalty is imposed. When a donor or an acceptor is buried with no intramolecular hydrogen bond formed, an energetic penalty is imposed. We examine all the donors and acceptors for backbone-backbone, backbone-side chain, and side chain-side chain intramolecular hydrogen bonds and calculate the TDP. Our free-energy function has been tested for three different decoy sets. It is better than any other physics-based or knowledge-based potential function in terms of the accuracy in discriminating the native fold from misfolded decoys and the achievement of high Z-scores. Proteins 2009. © 2009 Wiley-Liss, Inc.

The full text of this article hosted at iucr.org is unavailable due to technical difficulties.