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Theoretical studies on transimination of vitamin B6 analogs
Author(s) -
Salvà Antoni,
Donoso Josefa,
Frau Juan,
Muñoz Francisco
Publication year - 2002
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.10188
Subject(s) - geminal , chemistry , solvation , molecule , computational chemistry , mindo , transition state , implicit solvation , methylamine , hydrogen bond , reaction coordinate , thermodynamics , stereochemistry , organic chemistry , catalysis , physics
The transimination reaction of vitamin B6 analogs has been studied by semiempirical quantum mechanics calculations (PM3 Hamiltonian) on a model reactive system consisting of the Schiff base made from a pyridoxal‐5'‐phosphate (PLP) model compound, methylamine and two auxiliary water molecules. The mechanism of this reaction has been theoretically established through the description of the energy and the geometric parameters of the intermediates and transition‐state structures in the gas phase and in water solution by means of the use of two different solvation models. The description of the reaction pathway for transimination through the structures that have resulted from the calculations supports the existence of a geminal diamine as the main intermediate. The reaction also involves the occurrence of internal hydrogen transfers and water‐mediated hydrogen transfers as rate‐limiting steps. This study highlights the key role of water molecules not only in the formation of selected hydrogen bonds but also as true reactives. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002