Rates and mechanism of biphenyl synthesis catalyzed …

Oral administration of a commercial PCB mixture to chickens caused a hepatic-type porphyria characterized by hepatic accumulation and urinary excretion of uroporphyrin. To clarify the mechanism of the porphyrinogenic activity of these PCBs, we studied the structural requirementof synthetic PCB for porphyrinogenic activities by using the cultured chick embryo liver cells and examined the relationship between induction of 8-aminolevulinic acid (ALA) synthetase and inhibition of uroporphyrinogen decarboxylase. We established that the porphyrinogenic effect of PCBs exhibits a sharply defined structure-activity relationship in that only 3,4,3',4'-tetrachlorobiphenyl and 3,4,5,3',4',5'-hexachlorobiphenyl produced a marked accumulation of uroporphyrin. We also demonstrated that in ALA-supplemented cultures, these same compounds lead to accumulation of a large amount of uroporphyrin III, whereas with other PCBs, which were weak inducers of porphyrin synthesis, the accumulated porphyrin was mostly protoporphyrin. Kinetic studies of the sequential decarboxylation of uroporphyrinogen with purified uroporphyrinogen decarboxylase were performed. The 3,4,3',4'-tetrachlorobiphenyl and 3,4,5,3',4',5'-hexachlorobiphenyl strongly inhibit uroporphyrinogen decarboxylase directly at two steps, i.e. first in the formation of hexacarboxylic porphyrinogen III from heptacarboxylic porphyrinogen III and second in the formation of

find application as ligands in asymmetric synthesis

M., Synthesis of bio-inspired hybrid polymers using peptide synthesis and protein engineering.

Synthesis description for preparation of BIPHENYL

R., Activity-Based Protein Profiling Reagents for Protein Arginine Deaminase 4 (PAD4): Synthesis and in vitro Evaluation of a Fluorescently Labeled Probe.

The side product has been produced is biphenyl which consists ..

B., Synthesis of azide-alkyne fragments for click' chemical applications; formation of oligomers from orthogonally protected trialkylsilyl-propargyl azides and propargyl alcohols.

A., Selective Dye-Labeling of Newly Synthesized Proteins in Bacterial Cells.

methyl propionate, 554-12-1 - The Good Scents Company

PCBs are synthetic chlorinated hydrocarbon compounds that consist of two benzene rings linked by a single carbon–carbon bond, with from 1 to all 10 of the hydrogen atoms replaced with chlorines. PCBs have been produced commercially since 1929. They have been used in plasticizers, surface coatings, inks, adhesives, flame retardants, pesticide extenders, paints, and microencapsulation of dyes for carbonless duplicating paper. Because PCBs resist both acids and alkalis and are relatively heat-stable, they have been used in dielectric fluids in transformers and capacitors. Further environmental contamination may occur from the disposal of old electrical equipment containing PCBs. The pyrolysis of PCB mixtures produces hydrogen chloride and polychlorinated dibenzofurans (PCDFs), and pyrolysis of mixtures containing chlorobenzenes also produces polychlorinated dibenzodioxins (PCDDs). Many countries have severely restricted or banned the production of PCBs.

J., A facile synthesis of the GalNAcß1-4Gal target sequence of respiratory pathogens.

a sophomore organic chemistry experiment

The facility with which the aromatic ring of phenols and phenol ethers undergoes electrophilic substitution has been noted. Two examples are shown in the following diagram. The first shows the Friedel-Crafts synthesis of the food preservative BHT from para-cresol. The second reaction is interesting in that it further demonstrates the delocalization of charge that occurs in the phenolate anion. Carbon dioxide is a weak electrophile and normally does not react with aromatic compounds; however, the negative charge concentration on the phenolate ring enables the carboxylation reaction shown in the second step. The sodium salt of salicylic acid is the major ptoduct, and the preference for ortho substitution may reflect the influence of the sodium cation. This is called the Kolbe-Schmidt reaction, and it has served in the preparation of aspirin, as the last step illustrates.

Labeling, Detection and Identification of Newly Synthesized Proteomes with Bioorthogonal Non-Canonical Amino-Acid Tagging.

Mechanism of Action of Biphenyl-Ketoaldehyde Derivatives

Polyphenylene (PP) was electrochemically synthesized from biphenyl under a centrifugal field (315 g) and Earth's gravity (1 g). The polymerization rate of biphenyl (BP) was found to be increased by the applied gravitational force. PP films thus synthesized on electrodes with and without centrifugation also exhibited clear differences in their physical and chemical properties. In addition, morphological structure of the film was also affected by the centrifugal field. A mechanism for the electrochemical deposition of PP film under the centrifugal force has also been proposed.

B.; Wong, C.-h., Rapid diversity-oriented synthesis in microtiter plates for in situ screening of HIV protease inhibitors.

Molecules | April 2014 - Browse Articles

In addition, the methyl sulfone PCBs have been shown to inhibit the CYP11B enzyme activity in the adrenals of mice and grey seals (). This type of mechanism could explain the observed modulation of glucocorticoid synthesis (Johansson et al., 1998a,b). Furthermore, reproductive toxicity, interaction with the estrogen receptor, and pulmonary metabolism have been observed after exposure to methyl sulfone PCBs (Letcher et al., 2000).