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Conformational transition states of a β‐hairpin peptide between the ordered and disordered conformations in explicit water
Author(s) -
Kamiya Narutoshi,
Higo Junichi,
Nakamura Haruki
Publication year - 2002
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.0213102
Subject(s) - energy landscape , folding (dsp implementation) , chemistry , hydrogen bond , crystallography , chemical physics , molecular dynamics , plateau (mathematics) , transition state , protein folding , saddle point , computational chemistry , molecule , geometry , mathematical analysis , biochemistry , mathematics , organic chemistry , electrical engineering , engineering , catalysis
The conformational transition states of a β‐hairpin peptide in explicit water were identified from the free energy landscapes obtained from the multicanonical ensemble, using an enhanced conformational sampling calculation. The β‐hairpin conformations were significant at 300 K in the landscape, and the typical nuclear Overhauser effect signals were reproduced, consistent with the previously reported experiment. In contrast, the disordered conformations were predominant at higher temperatures. Among the stable conformations at 300 K, there were several free energy barriers, which were not visible in the landscapes formed with the conventional parameters. We identified the transition states around the saddle points along the putative folding and unfolding paths between the β‐hairpin and the disordered conformations in the landscape. The characteristic features of these transition states are the predominant hydrophobic contacts and the several hydrogen bonds among the side‐chains, as well as some of the backbone hydrogen bonds. The unfolding simulations at high temperatures, 400 K and 500 K, and their principal component analyses also provided estimates for the transition state conformations, which agreed well with those at 400 K and 500 K deduced from the current free energy landscapes at 400 K and 500 K, respectively. However, the transition states at high temperatures were much more widely distributed on the landscape than those at 300 K, and their conformations were different.