Conformational free energy of hydration for the alanine dipeptide: Thermodynamic analysis

Bernard Pettitt, Martin Karplus

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Abstract

The intramolecular potential of mean force surface obtained for the alanine dipeptide, N-acetylalanine N′-methylamide, in aqueous solution by the use of the extended RISM integral equation theory is decomposed into its energetic and entropic contributions by determining the temperature derivative of the free energy. The solvation energy is most important but the solvation entropy is also significant in determining the position of the minima on the surface. Most barriers are found to be enthalpically dominated. The change in the various interactions (solvent-solvent and solute-solvent) is analyzed. The intramolecular solvent-modified surface has a substantial contribution from the temperature dependence of the solvent dielectric constant.

Original languageEnglish (US)
Pages (from-to)3994-3997
Number of pages4
JournalJournal of Physical Chemistry
Volume92
Issue number13
StatePublished - 1988
Externally publishedYes

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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