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At least 1,711 records · Page 95Linked to original sources
PubMed1996

[Evaluation of environmental exposure on persistent and toxic organic halogens].

The environmental concentrations of the persistent organohalogen compounds has been presented basing on the own results which were compared with the data published by the other authors. The predicted exposure of Polish population to PCDDs and PCDFs including combustion processes as a main potential source of the exposure has also been discussed. Analysis of the breast milk from Silesia region in Poland showed no substantial difference as compared to milk in other European countries.

Adipose Tissue↗
PubMed1996

Halogenated benzimidazole inhibitors of phosphorylation, in vitro and in vivo, of the surface acidic proteins of the yeast ribosomal 60S subunit by endogenous protein kinases CK-II and PK60S.

Several halogeno benzimidazoles and 2-azabenzimidazoles, previously shown to be relatively selective inhibitors of protein kinases CK-I and/or CK-II from various sources, including CK-II from yeast [Szyszka et al. (1995) Biochem. Biophys. Res. Commun. 208, 418-424] inhibit also the yeast ribosomal protein kinase PK60S. The most effective inhibitor of CK-II and PK60S was tetrabromo-2-azabenzimidazole ](TetraBr-2-azaBz), which was competitive with respect to ATP (and GTP in the case of CK-II) with Ki values of 0.7 microM for CK-II, and 0.1 microM for PK60S PK60S phosphorylates only three (YP1 beta', YP2 alpha) out of five polypeptides of pp13 kDa acidic proteins of 60S subunit phosphorylated by CK-II [Szyszka et al. (1995) Acta Biochim. Polon. 42, 357-362]. Accordingly, TetraBr-2-azaBz inhibits phosphorylation only of these polypeptides, catalysed by PK60S . Addition of TetraBr-2-azaBz to cultures of yeast cells, at concentrations which were without effect on cell growth, led to inhibition of intracellular phosphorylation of ribosomal acidic proteins, paralleling that observed in vitro. TetraBr-2-azaBz is shown to be a useful tool for studies on the intracellular regulation of phosphorylation of the ribosomal 60S acidic proteins, which are involved in formation of active ribosomes.

Benzimidazoles↗
PubMedDate not supplied

Metabolism of halogenated methanes and macromolecular binding.

Dihalomethanes are metabolized to carbon monoxide both in vivo and in vitro. The reaction is catalyzed by a hepatic microsomal cytochrome P-450 dependent mixed function oxidase system. Bioorganic mechanism studies suggest an initial oxygen insertion reaction followed by rearrangement to a formyl halide intermediate which in turn decomposes to yield carbon monoxide. In vitro studies show that 14C-dichloromethane becomes covalently bound to both microsomal protein and lipid. The similar characteristics of metabolism to carbon monoxide and covalent binding suggests that a common intermediate, perhaps the formyl halide, may be involved. Dihalomethanes are also metabolized to formaldehyde, formic acid, and inorganic halide. A glutathione transferase, located in hepatic cytosol fractions, appears to be involved. Reaction mechanism studies suggest that a S-hydroxymethyl glutathione intermediate may yield formaldehyde or be diverted via formaldehyde dehydrogenase/S-formyl glutathione hydrolase to yield formic acid. Haloforms are also metabolized in vitro to carbon monoxide by a hepatic microsomal cytochrome P-450 dependent mixed function oxidase system. This reaction is a markedly stimulated by sulfhydryl compounds.

Animals↗
PubMed2000

Introduction of heteroatom-based substituents into 1,4-dihydropyridines by means of a halogen-mediated, oxidative protocol: diamination, sulfonylation, sulfinylation, bis-sulfanylation, and halo-phosphonylation processes

The natural tendency of 1,4-dihydropyridines to undergo "biomimetic" oxidation to afford pyridinium salts can be switched off and, through the use of reagents that interact electrophilically with the enamine moiety present in the heterocyclic system, it is possible to promote alternative oxidations. In this way, efficient regio- and stereocontrolled synthetic methods have been developed that lead to diversely substituted di- and tetrahydropyridines. These include iodoazidation, diamination, bis-sulfonamidation, sulfonylation, sulfinylation, thiocyanation, sulfanylation, bis-sulfanylation, and halo-phosphonylation processes.

Journal Article↗
PubMed1999

Prereactive Complexes of Dihalogens XY with Lewis Bases B in the Gas Phase: A Systematic Case for the Halogen Analogue B small middle dot small middle dot small middle dotXY of the Hydrogen Bond B small middle dot small middle dot small middle dotHX.

Similar and yet also notably different are the B small middle dot small middle dot small middle dotXY and B small middle dot small middle dot small middle dotHX complexes in the gas phase, where B is a simple Lewis base, XY is a homo- or heterodihalogen molecule, and HX is a hydrogen halide. This is demonstrated, for example, by the structures of oxirane small middle dot small middle dot small middle dotClF and oxirane small middle dot small middle dot small middle dotHCl (see picture). Both bonds are dominated by simple electrostatic interactions, but differ in terms of their propensity for nonlinearity.

Journal Article↗