In Ni(0)-catalyzed carboxylation reaction of aryl chloride with CO2, the formation of a Ni(I) species is crucial, because the CO2 insertion into the Ni(I)-Ph bond easily occurs but that into the Ni(II)-Ph bond cannot. This is a key point of this successful carboxylation reaction.

The formation of vitamin K epoxide and the vitamin K-dependent carboxylation of glutamic acid residues present in synthetic substrates and decarboxyprothrombin are both inhibited by superoxide dismutase. Catalase only inhibits the generation of vitamin K epoxide, suggesting that the carboxylation and epoxidation reactions are not inter-dependent.

Acetone degradation by cell suspensions of Desulfococcus biacutus was CO2 dependent, indicating initiation by a carboxylation reaction, while degradation of 3-hydroxybutyrate was not CO2 dependent. Growth on 3-hydroxybutyrate resulted in acetate accumulation in the medium at a ratio of 1 mol of acetate per mol of substrate degraded. In acetone-grown cultures no coenzyme A (CoA) transferase or C...

Vitamin K-dependent (VKD) proteins require modification by the VKD-gamma-glutamyl carboxylase, an enzyme that converts clusters of glus to glas in a reaction that requires vitamin K hydroquinone, for their activity. We have discovered that the carboxylase also carboxylates itself in a reaction dependent on vitamin K. When pure human recombinant carboxylase was incubated in vitro with 14CO2 and ...

Nitrogen is a dominant regulator of vegetation dynamics, net primary production, and terrestrial carbon cycles; however, most ecosystem models use a rather simplistic relationship between leaf nitrogen content and photosynthetic capacity. Such an approach does not consider how patterns of nitrogen allocation may change with differences in light intensity, growing-season temperature and CO(2) co...

TADA, K. and ARAKAWA, Ts. Hyperglycinemia and propionate carboxylation. Tohoku J. exp. Med., 1970, 102 (3), 313-314 The oxidation of propionate and methylmalonate was investigated in leukocytes from a patient with hyperglycin emia. It was found that the patient's leukocytes could oxidize both propionate and methylmalonate normally. These findings suggest that hyperglycinemia con sists of primar...

Technical Papers Relation of Prothrombin to the Prolongation of Clotting Timiie in Aestivating Ground Squirrels: Arthur Svihla, Howard Bowman, and Ruth Ritenour . ............................... 306 Inactivation of Influenza Virus and of Viral Hemiiagglutinin by the Ciliate Tetrahymena geleii: Vincent Groupe' and Leonora H. Pugh........ . ........... ... . 307 The Importance of Protective Urina...

In order to extend the applicability of the regioselective enzymatic carboxylation of phenols, the substrate scope of o-benzoic acid (de)carboxylases has been investigated towards complex molecules with an emphasis on flavouring agents and polyphenols possessing antioxidant properties. o-Hydroxycarboxylic acid products were obtained with perfect regioselectivity, in moderate to excellent yields...

A mathematical model is developed which can be used to predict in vivo carbon isotope fractionations associated with carbon fixation in plants in terms of diffusion, CO(2) hydration, and carboxylation components. This model also permits calculation of internal CO(2) concentration for comparison with results of gas-exchange experiments. The isotope fractionations associated with carbon fixation ...

Urea carboxylase, an avidin-sensitive enzyme catalyzing the ATP-dependent carboxylation of urea, has been shown to catalyze this reaction in a sequence of at least two steps. In the presence of all of the required carboxylation cofactors except urea, an enzyme-CO2 complex is formed. This complex was isolated by Sephadex chromatography and was capable, in the absence of added cofactors, of trans...