1225267-40-2Relevant articles and documents
Kinetic studies on oxidation of l-cysteine and 2-mercaptoethanol by a trinuclear Mn(IV) species in aqueous acidic media
Chakraborty, Maharudra,Mandal, Pulak Chandra,Mukhopadhyay, Subrata
, p. 77 - 82 (2013)
In aqueous media, the trinuclear MnIV complex, [Mn IV3(μ-O)4(phen)4(H 2O)2]4+ (phen = 1,10-phenanthroline) (1) behaves like a monobasic acid, equilibrates with its deprotonated conjugate base (2) (12 + H+, pKa = 4.00 (± 0.15) at 25.0 °C, I = 1.0 M, maintained with NaNO3). An aqueous solution of 1 in the pH range 2.2-4.0 smoothly oxidizes 2-mercaptoethanol (mercap) and l-cysteine (cys) to their respective disulfides; itself being reduced to [Mn(phen) 3]2+ in presence of excess 1,10-phenanthroline which also masks Cu2+, if any, present in the reaction media as impurity as well as acting as a buffer that controls pH range during the reaction. The observed rate constants in H2O media were found to be considerably lowered in media enriched with D2O and a proton-coupled single electron transfer rate step is proposed. Interestingly, we found that deprotonated oxidant (2) reacts faster than the protonated species (1) in oxidizing both the thiols.
Chiro-optical properties of sulfur containing amino acids
Jung,Ottnad,Rimpler
, p. 436 - 444 (1973)
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N-Salicylideneamino acidato complexes of oxovanadium(IV). the cysteine and penicillamine complexes
Pessoa, Joao Costa,Calhorda, Maria J.,Cavaco, Isabel,Costa, Paulo J.,Correia, Isabel,Costa, Dina,Vilas-Boas, Luis F.,Felix, Vitor,Gillard, Robert D.,Henriques, Rui T.,Wiggins, Robert
, p. 2855 - 2866 (2007/10/03)
Oxovanadium(iv) complexes with ligands derived from the reaction of salicylaldehyde with L-cysteine and with D- and D,L-penicillamine are prepared. The compounds are characterised by elemental analysis, spectroscopy (UV-VIS, CD, EPR), TG, DSC and magnetic susceptibility measurements (9-295 K). We discuss several aspects related to the structure of these complexes in the solid state and in solution; in particular, the possibility of forming thiazolidine complexes, and their comparison with the characterised complexes is studied by molecular mechanics and density functional theory calculations. The solution structures depend on pH and solvent, and while with L-Cys the spectroscopic results show trends similar to those of the L-Ala and L-Ser systems up to ca. pH 8-9, where thiolate coordination starts being detected, the penicillamine system is quite distinct, namely thiolate coordination occurs for pH > 6.5. In the presence of salicylaldehyde and VIVO the desulfydration of cysteine proceeds rapidly, but no similar reaction occurs with penicillamine, although its decomposition is also activated. The DFT calculations do not indicate any energetic basis for this distinct reactivity, which possibly results from different complexes present in the Cys and Pen systems. In the cysteine system, the N-salicylidene dehydroalanine-VIVO complex V is believed to form in an intermediate stage of the desulfydration. Further, addition of several nucleophiles to the cysteine reaction mixtures produce amino acid derivatives by a Michael-type base-catalysed addition, a result compatible with the formation of V. The products of these reactions were analysed by TLC and HPLC, and in some cases isolated.
