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Theoretical insights into the thiol reductase activity of ebtellur
Author(s) -
Sakimoto Yukiko,
Hirao Kimihiko,
Musaev Djamaladdin G.
Publication year - 2009
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.22158
Subject(s) - chemistry , thiol , exothermic reaction , enthalpy , molecule , activation barrier , density functional theory , stereochemistry , medicinal chemistry , crystallography , computational chemistry , organic chemistry , thermodynamics , physics
Reductase activity of ebtellur was studied at the density functional level. For this purpose, the mechanism and controlling factors of the reactions EbTeO + 2GSH → EbTe + GS‐SG + H 2 O (2) and EbTeO + H 2 O + 2GSH → EbTe(OH) 2 + 2GSH → EbTe + GS‐SG + 2H 2 O (3) were analyzed. It was shown that the addition of the first thiol molecule to 2_TeO (model of EbTeO), which occurs with a few kcal/mol activation barrier and exothermic by 20–25 (9–13) kcal/mol, leads to 2_TeO, 2_Te(OH)(SMe), II, intermediate. Addition of the next thiol molecule to II may proceed via the both “concerted” and “stepwise” pathways with a rate‐determining SS bond formation step. It was found that the “concerted” pathway is slightly favorable at the enthalpy level than the “stepwise” pathway. Overall reaction (2) is found to be exothermic by 41.6 (41.4) kcal/mol. Calculations show that the MeSH bond activation by oxo species, 2_TeO, is much easier process than that by dihydroxy species, 2_Te(OH) 2 . Comparison of the calculated barriers for rate‐determining steps of the reaction 2_TeO + 2 MeSH with that, 19.4 (30.3) kcal/mol, for the reaction 2_TeO + H 2 O + 2 MeSH → 2_Te(OH) 2 + MeSH indicates that in the presence of water molecule ebtellur should show less (slow) thiol reductase activity. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009