- Studies on the air oxidation of some arsenic(III) compounds
-
The air oxidation of As(III) oxides [(PhAsO)x and Ph 2As-O-AsPh2] and thioesters [Ph-As(SPh)2, Ph2As-SPh Me-As(SPh)2, Me2As-SPh], in chloroform and in methanol was studied. The air oxidation in chloroform was faster probably because the solubility of dioxygen is greater than in methanol, and it is favored by the electron-withdrawing phenyl groups bound to As(III). The products obtained were the arsonic or arsinic acids and diphenyl disulfide. In one case, diphenyl disulfide and thiophenol were produced. The results can be rationalized by assuming first hydrolysis of the As(III) compounds to arsonous or arsinous acids followed by their oxidation to arsonic and arsinic acids, which should involve the binding of dioxygen to As(III). The other hypothesis assumes first the binding of dioxygen to As(III) of these oxides and thioesters followed by the decomposition of the adducts. The binding of the ground state dioxygen to As(III) may have biochemical implications for toxicity or chemotherapy of arsenic(III) compounds. Copyright Taylor & Francis Group, LLC.
- Sideris, Theodore D.,Ioannou, Panayiotis V.
-
-
Read Online
- Enzymatic methylation of arsenic compounds: Assay, partial purification, and properties of arsenite methyltransferase and monomethylarsonic acid methyltransferase of rabbit liver
-
A rapid, accurate, in vitro assay utilizing radioactive S-adenosylmethionine (SAM) has been developed for the methylation of arsenite and monomethylarsonate (MMA) by rabbit liver methyltransferases. The assay has been validated by separating, identifying, and measuring the products of the reaction using chloroform extraction, ion exchange chromatography, TLC, or HPLC. The enzymes involved in this pathway, arsenite methyltransferase and MMA methyltransferase, have been purified approximately 2000-fold from rabbit liver. After gel electrophoresis, a single band is obtained with both enzyme activities in it. The pH optima for purified arsenite methyltransferase and monomethylarsonic acid methyltransferase are 8.2 and 8.0, respectively. A thiol, S-adenosylmethionine, and arsenite are required for the partially purified arsenite methyltransferase that catalyzes the synthesis of monomethylarsonate. A different enzyme activity that catalyzes the methylation of monomethylarsonate to dimethylarsinate also requires SAM and a thiol. Even though arsenite methyltransferase and monomethylarsonate methyltransferase have different substrates, pH optima, and saturation concentrations for their substrates, whether the two activities are present on one protein molecule or different protein molecules is still uncertain. Both activities have a molecular mass of 60 kDa as determined by gel exclusion chromatography. There is no evidence at the present time for these enzyme activities being on different protein molecules. Neither arsenate, selenate, selenite, or selenide are methylated by the purified enzyme preparations. Results from the use of crude extracts, often called cytosol, to study the properties of these methyltransferases dealing with arsenic species should be viewed with caution since such crude extracts contain inhibiting and other interfering activities.
- Zakharyan,Wu,Bogdan,Aposhian
-
-
Read Online
- METHOD FOR ANALYZING PSA, AND A METHOD FOR DISTINGUISHING PROSTATE CANCER FROM PROSTATIC HYPERTROPHY USING THAT METHOD FOR ANALYZING PSA
-
A method for distinguishing prostate cancer from prostatic hypertrophy using the method for analyzing PSA and an analysis kit of PSA are provided. An object of the present invention can be solved by being brought into contact a lectin having an affinity for β-N-acetylgalactosamine residues with a sample possibly containing PSA, to determine an amount of PSA having an affinity for the lectin. A method for distinguishing prostate cancer from prostatic hypertrophy can be provided by this method.
- -
-
-
- Microorganisms for the production of methacrylic acid
-
The invention provides a non-naturally occurring microbial organism having a 2-hydroxyisobutyric acid, 3-hydroxyisobutyric acid or methacrylic acid pathway. The microbial organism contains at least one exogenous nucleic acid encoding an enzyme in a 2-hydroxyisobutyric acid, 3-hydroxyisobutyric acid or methacrylic acid pathway. The invention additionally provides a method for producing 2-hydroxyisobutyric acid, 3-hydroxyisobutyric acid or methacrylic acid. The method can include culturing a 2-hydroxyisobutyric acid, 3-hydroxyisobutyric acid or methacrylic acid producing microbial organism expressing at least one exogenous nucleic acid encoding a 2-hydroxyisobutyric acid, 3-hydroxyisobutyric acid or methacrylic acid pathway enzyme in a sufficient amount and culturing under conditions and for a sufficient period of time to produce 2-hydroxyisobutyric acid, 3-hydroxyisobutyric acid or methacrylic acid.
- -
-
-
- Ampholytic copolymer based on quaternized nitrogen-containing monomers
-
The present invention relates to an ampholytic copolymer based on quaternized nitrogen-containing monomers which has a molar excess of cationogenic/cationic groups compared to anionogenic/anionic groups, to cosmetic or pharmaceutical compositions which comprise at least one such ampholytic copolymer, and to further uses of these copolymers.
- -
-
-
- CATALYST FOR LIVING RADICAL POLYMERIZATION
-
Provided is a catalyst used for a living radical polymerization method, which contains a central element consisting of carbon and at least one halogen atom binding to the central element. Further, a hydrocarbon compound can be used as a catalyst precursor. A monomer having a radical-reactive unsaturated bond is subjected to a radical polymerization reaction in the presence of the catalyst, consequently a polymer having narrow molecular weight distribution can be obtained, and thus the cost of the living radical polymerization can be remarkably reduced. The present invention is significantly more environmentally friendly and economically excellent than conventional living radical polymerization methods, due to advantages such as low toxicity of the catalyst, low amount of the catalyst used, high solubility of the catalyst, mild reaction conditions, and no coloration/no odor (no need of any post-treatments for a molded article), and the like.
- -
-
-
- Process for separating pivalic acid from spent reaction mixtures
-
A process for recovering 2,2-dimethylpropanoic acid in highly pure form from a mixture of 2,2-dimethylpropanoic acid and impurities which may be obtained in the production of a beta lactam antibiotic, by degrading impurities and separating off the volatile fragments.
- -
-
-
- Process for manufacturing crystalline calcium magnesium acetate
-
A process is provided for making bulk calcium magnesium acetate in a substantially pure crystalline form. The crystalline CMA contains less than about 0.5% of water soluble impurities.
- -
-
-
- Process for producing N-(halomethyl)acylamides
-
The disclosure herein relates to a new process for the preparation of N-(halomethyl)acylamides by reacting the corresponding N-(alkoxymethyl)acylamide with thionyl chloride or thionyl bromide in the presence of a Lewis Acid catalyst.
- -
-
-
