- Kinetics and mechanism of the formation and reactions of S-nitroso derivatives of some heterocyclic thiones
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Rate and equilibrium measurements have been obtained for the nitrosation (using nitrous acid in dilute acid aqueous solution) of the following thione-thiol nitrogen heterocyclic species and for the decomposition reactions of the formed S-NO- io
- Amado,Blakelock,Holmes,Williams
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- Protein Folding Stability Changes across the Proteome Reveal Targets of Cu Toxicity in E. coli
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The ability of metal ionophores to induce cellular metal hyperaccumulation endows them with potent antimicrobial activity; however, the targets and mechanisms behind these outcomes are not well understood. This work describes the first utilization of proteome-wide measurements of protein folding stability in combination with protein expression level analysis to identify protein targets of copper, thereby providing new insight into ionophore-induced copper toxicity in E. coli. The protein folding stability analysis employed a one-pot protocol for pulse proteolysis (PP) in combination with a semi-tryptic peptide enrichment strategy for proteolysis procedures (STEPP) to generate stability profiles for proteins in cell lysates derived from E. coli exposed to copper with and without two ionophores, the antimicrobial agent pyrithione and its β-lactamase-activated prodrug, PcephPT. As part of this work, the above cell lysates were also subject to protein expression level analysis using conventional quantitative bottom-up proteomic methods. The protein folding stability and expression level profiles generated here enabled the effects of ionophore vs copper to be distinguished and revealed copper-driven stability changes in proteins involved in processes spanning metabolism, translation, and cell redox homeostasis. The 159 differentially stabilized proteins identified in this analysis were significantly more numerous (~3×) than the 53 proteins identified with differential expression levels. These results illustrate the unique information that protein stability measurements can provide to decipher metal-dependent processes in drug mode of action studies.
- Wiebelhaus, Nancy,Zaengle-Barone, Jacqueline M.,Hwang, Kevin K.,Franz, Katherine J.,Fitzgerald, Michael C.
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- A desymmetrization approach toward highly oxygenated cis-decalins
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The cis-decalin core 2 of the antibiotic branimycin has been prepared by desymmetrization of diepoxynaphthalene 4. The key steps involve two successive SN' opening of the oxa-bridges. An improved procedure for the synthesis of 4 Is also described.
- Gromov, Alexey,Enev, Valentin,Mulzer, Johann
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supporting information; experimental part
p. 2884 - 2886
(2009/12/24)
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- Chemistry of Mercaptopyridines and Related Ligands. Part 3. Novel Examples of Copper(II)-Tertiary Phosphine Complexes stabilized by 1-Hydroxypyridine-2-thione
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reaction of 1-hydroxypyridine-2-thione (C5H5NOS) with copper(II) chloride dihydrate gave an insoluble dirty yellow compound of stoichiometry, 1 which is ESR active.Similar reaction with copper(II) bromide gave the ESR-active green compound 7.Reactions of 1 and 7 with tertiary phosphines gave mixed-ligand complexes of stoichiometry CuX(C5H4NOS)Ln , all of which are ESR active.The latter complexes represent the first novel examples of air- and moisture-stable copper(II)-tertiary phopshine complexes in which Cu(II) is bonded to one halogen, one oxygen, one sulfur and two phosphorus atoms.
- Lobana, Tarlok S.,Bhatia, Paramjit K.
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p. 1407 - 1410
(2007/10/02)
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- Synthesis of Disulfides via Sulfenylation of Alkyl and Aryldithiopyridine N-Oxides
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Alkyl and aryldithiopyridine N-oxides were prepared by reaction of 2,2'-dithiopyridine-1,1'-dioxide with various thiols in high yields.Some of the mixed disulfide products could in turn be used to sulfenylate efficiently other thiols.Therefore, practical and efficient synthetic methods for both symmetrical and unsymmetrical disulfides were developed.
- Barton, Derek H. R.,Chen, Chen,Wall, G. Michael
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p. 6127 - 6138
(2007/10/02)
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- THE INVENTION OF NEW RADICAL CHAIN REACTIONS. PART VIII. RADICAL CHEMISTRY OF THIOHYDROXAMIC ESTERS; A NEW METHOD FOR THE GENERATION OF CARBON RADICALS FROM CARBOXYLIC ACIDS.
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The aliphatic and alicyclic esters of N-hydroxy-pyridine-2-thione are readily reduced by tributylstannane in a radical chain reaction to furnish nor-alkanes.In the absence of the stannane a smooth decarboxylative rearrangement occurs to give 2-substituted thiopyridines.The radicals present in this reaction provoke with t-butylthiol an efficient radical reaction with formation of nor-alkane and 2-pyridyl-t-butyl disulphide.Similarly these carbon radicals can be captured by halogen atom transfer to give noralkyl chlorides, bromides and iodides.With oxygen in the presence of t-butylthiol the corresponding noralkyl hydroperoxides are formed in another radical chain reaction.
- Barton, Derek H. R.,Crich, David,Motherwell, William B.
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p. 3901 - 3924
(2007/10/02)
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