Thiol

Glutathione is a small redox-active molecule existing in two main stable forms: the thiol (GSH) and the disulphide (GSSG). In plants growing in optimal conditions, the GSH:GSSG ratio is high in most cell compartments. Challenging environmental conditions are known to alter this ratio, notably by inducing the accumulation of GSSG, an effect that may be influential in the perception or transduction of stress signals. Despite the potential importance of glutathione status in redox signaling, the reactions responsible for the oxidation of GSH to GSSG have not been clearly identified. Most attention has focused on the ascorbate-glutathione pathway, but several other candidate pathways may couple the availability of oxidants such as H2O2 to changes in glutathione and thus impact on signaling pathways through regulation of protein thiol-disulfide status. We provide an overview of the main candidate pathways and discuss the available biochemical, transcriptomic, and genetic evidence relating to each. Our analysis emphasizes how much is still to be elucidated on this question, which is likely important for a full understanding of how stress-related redox regulation might impinge on phytohormone-related and other signaling pathways in plants.

A sequential ligand addition to the aluminum (III) cation has been studied using the B3LYP functional and a combined allelectron/pseudopotentials basis set. The aluminum complexes are compared with analogous magnesium (II) complexes. Different thermodynamical data, such as incremental binding energies, enthalpies, entropies and free energies, are presented for these addition reactions. While the magnesium (II) cation can only accommodate three negatively charged ligands, aluminum (III) accommodates four even after including bulk solvent effects. The main differences between both cations complexing with the neutral ligands, is that aluminum (III) is not able to form complexes with methanol until the number of methanol ligands is equal to 3. Magnesium (II) prefers to bind methanol and formamide when the number of ligands is small, while aluminum prefers formamide. For the largest complexes both cations prefer to bind water.

The synthesis and physico-chemical characteristics of thiol-functionalized mesoporous silicates MCM-41 and SBA-15 are described. The sorption properties of the materials with respect to noble metal ions, in particular palladium(II) from hydrochloric acid solutions have been studied. The materials obtained have been characterized using a complex of physical and chemical methods before and after functionalization. The evaluation of the sorption capacity of the obtained sorbents with respect to Pd(II) ions has been performed. Experimental results show high sorption activity of thiol-functionalized mesoporous silica.

ABSTRACT. Tripropylammonium fluorochromate(VI) (TPAFC) is an efficient and novel reagent, which can be prepared easily and oxidizes thiols to the corresponding disulfides, quickly. The reactions are performed cleanly and are controlled to stop at the disulfide stage, without over-oxidation or side products. Coupling of thiols to their corresponding disulfides, was studied in solution at room temperature and under conditions using a minimal amount of solvent under microwave irradiation. The easy procedure, simple work-up, short reaction times, and excellent yields are other advantages of this reagent.