蛋白質コンホメーションの安定性と水和の重要性

概要

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The driving forces to fold a nascent polypeptide chain from the random coil to the native conformation discussed so far have been intramolecular interactions between constituent atoms against the entropy of the chain favorable for the random state. Since the accessible surface area of the native packed conformation is much less than that of the random coil, hydration free energy is expected to be favorable for the random coil. Utilizing the linear relationships between thermodynamic quantities and accessible surface area of atomic groups in a protein, the quantities associated with hydration could be evaluated quantitatively. Furthermore, chain enthalpy and entropy in vacuum originated from intramolecular interactions and flexibility of the chain could be estimated from thermodynamic quantities of hydration upon unfolding, and experimental values of transition temperature and unfolding enthalpy on 12 proteins of known three-dimensional structure. The results show that a large hydration free energy compensates a large chain free energy, resulting in a small unfolding free energy. Thus, hydrated water around a protein molecule plays an essential role in the stabilization of the protein conformation.
日本生物物理学会の論文