Crystal structures of the isomeric dipeptides l-glycyl-l-me-thio-nine and l-me-thionyl-l-glycine.

The oxidation of me-thionyl peptides can contribute to increased biological (oxidative) stress and development of various inflammatory diseases. The conformation of peptides has an important role in the mechanism of oxidation and the inter-mediates formed in the reaction. Herein, the crystal structures of the isomeric dipeptides Gly-Met (Gly = glycine and Met = me-thio-nine) and Met-Gly, both CHNOS, are reported.

l-Me-thion-yl-l-tyrosine monohydrate.

The study of the oxidation of various proteins necessitates scrutiny of the amino acid sequence. Since me-thio-nine (Met) and tyrosine (Tyr) are easily oxidized, peptides that contain these amino acids are frequently studied using a variety of oxidation methods, including, but not limited to, pulse radiolysis, electrochemical oxidation, and laser flash photolysis. To date, the oxidation of the Met-Tyr dipeptide is not fully understood.

A co-crystal of nona-hydrated disodium(II) with mixed anions from m-chloro-benzoic acid and furosemide.

In the title compound, [Na2(H2O)9](C7H4ClO2)(C12H10ClN2O5S) {systematic name: catena-poly[[[triaquasodium(I)]-di-μ-aqua-[triaquasodium(I)]-μ-aqua] 3-chlorobenzoate 4-chloro-2-[(furan-2-ylmethyl)amino]-5-sulfamoylbenzoate]}, both the original m-chloro-benzoic acid and furosemide exist with deprotonated carboxyl-ates, and the sodium cations and water mol-ecules exist in chains with stoichiometry [Na2(OH2)9](2+) that propagate in the [-110] direction. Each of the two independent Na(+) ions is coordinated by three monodentate water mol-ecules, two double-water bridges, and one single-water bridge. There is considerable cross-linking between the [Na2(OH2)9](2+) chains and to furosemide sulfonamide and carboxyl-ate by inter-molecular O-H⋯O hydrogen bonds.

Prooxidant actions of bisphenol A (BPA) phenoxyl radicals: implications to BPA-related oxidative stress and toxicity.

We investigated the prooxidant effects of bisphenol A (BPA) phenoxyl radicals in comparison with the phenoxyl radicals of 3-tert-butyl-4-hydroxyanisole (BHA), 2,6-di-tert-butyl-methylphenol (BHT) and 4-tert-butylphenol (TBP). The phenoxyl radicals, generated in situ by 1-electron oxidation of the corresponding phenol, were allowed to react with reduced nicotinamide adenine dinucleotide phosphate (NADPH) and rifampicin. The antioxidant activity of various phenols was examined based on the reduction of 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH).