Thermodynamics and Dynamic Kinetics of the Oxidation of Selenomethionine to Methionine Selenoxide: A Dft Study

Abstract

In order to investigate the stability of selenomethionine (SeMet), the oxidation reaction of selenomethionine (SeMet) with an oxygen atom was studied by the density function theory (DFT) method. The structures of reactants, transition state and products were fully optimized at the B3LYP/6-311G** level. Intrinsic reaction coordinate (IRC) calculations were carried out to ensure the validity of the reaction path. The thermodynamic functions, namely entropy, enthalpy, free energy and equilibrium constant, and the reaction rate constant k in Eyring transition state theory, were also calculated. It has been shown that the SeMet oxidation process is favoured at lower temperatures, which might have implications for the storage stability of selenomethionine (SeMet) at lower temperatures.

Study of selenocompounds from selenium-enriched culture of edible sprouts

“…Organic Se 97 stock solutions were also prepared to a concentration of 1000 mg L -1 from selenocysteine 98 (SeCys 2 ), selenomethionine (SeMet) and selenomethyl-selenocysteine (SeMeSeCys) (Aldrich) 99 with HCl 0.5%. All the standard solutions were kept at 4ºC in closed opaque HDPE bottles, since 100 the stability of Se species depends on storage time and conditions, notably on exposure to air and 101 elevated temperature (Amoako et al, 2007;Liu & Bei, 2010). 102…”

Analytical Problems in Separation of Selenomethionine and Its Oxidative Product in HILIC HPLC

“…The SeMet oxidation process, which takes place during the extraction or storage of the sample, can be observed by the appearance of an additional signal on the chromatogram, with a simultaneous decrease in the intensity of the signal from SeMet [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. It was postulated that selenomethionine oxide (SeMetO) and methyloselenone are the possible reaction products.…”

“…Additives such as dithiothreitol (DTT) or β-mercaptoethanol (βME) are recommended to ensure that SeMet is kept in a reduced form. It has been shown that oxidation of SeMet was favored at lower temperatures, which might have implications for storage stability [ 17 , 23 ]. It is also postulated that the oxidation process of SeMet is strictly connected with enzymatic extraction [ 22 ].…”