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- Title
Theoretical study of environmental effects on proton transfer reaction through the peptide bond in a model system.
- Authors
Asada, Toshio; Takahashi, Tadayoshi; Koseki, Shiro
- Abstract
This study considered the possibility of proton transfer reactions through the peptide bond under different environments using the dipeptide and the 12-mer polyglycine α-helix models, in which diglycine is substituted by the 12-mer polyglycine helix. Ab initio molecular orbital calculations were carried out at the B3LYP/6-31+G(d) level of theory. To evaluate the free energies in solution, calculations of the solvation energies were performed using PCM. The correction functions on the calculated solvation energies were provided to reproduce experimental pKa values. The proton transfer reactions through the peptide bond are concluded to be possible in the protein for a wide range of proton acceptors. His complex has two free energy minima along a putative proton transfer pathway in spite of one minimum in the other complexes. The α-helix is estimated to suppress the proton transfer reactions through the peptide bond at the termini of the helix, although it is possible to proceed when the proton affinity of the acceptor is low.
- Subjects
PROTON transfer reactions; PEPTIDES; PHYSICAL &; theoretical chemistry; CHARGE transfer; CHEMICAL reactions
- Publication
Theoretical Chemistry Accounts: Theory, Computation, & Modeling, 2008, Vol 120, Issue 1-3, p263
- ISSN
1432-881X
- Publication type
Article
- DOI
10.1007/s00214-007-0301-y