Succinate ions reactions

Succinate is oxidized to fumarate by succinate dehydrogenase. 4 he hydrogen acceptor is FAD rather than NAD, which is used in the other three ox-ion reactions in the cycle. FAD is the hydrogen acceptor in this reaction... 

These experiments employing acidic media were at best only semi-quantitative, and none comprised a systematic investigation of the catalysis. Nevertheless, they placed the transformation in a new light and broadened the opportunities for investigating its mechanism. From the dependence of the reactions on the concentrations of formate, acetate, or succinate ions, Ashmarin argued for a general add and base catalysis. The results of Petuely s experiments implied the same kind of catalytic effect, and Petuely wrote the reaction as an enolization catalyzed by acids and bases. 

An example of competitive inhibition is the inhibition of succinate dehydrogenase by malonate ion. The catalyzed reaction is the oxidation of succinate ion to fumarate ion ... 

In the reaction involving succinate ions, owing to the very scarce solubility of copper succinate, numerous different procedures were tried, giving different results. Actually, five different derivatives were obtained and we were unable to satisfactorily characterize some other compounds [21]. As a matter of fact, we obtained three different 3D CPs, all based on the [Cu3(/u,3-OH)(/u-pz)3(Suc)] (Sue = succinate dianion) and differing for some small molecules (as water and Hpz) coordinated and/or present in the lattice. On the other hand, these very small differences produce largely different self-assemblies, almost impossible to forecast on the basis of the different reaction conditions, with a behavior analogous to that observed with compounds 3a-3c. Particularly, in one case, a PCP, with channels accounting for a 31% of vacuum space was obtained [21]. Moreover, a ID CP based on the [Cu(Suc)(Hpz)2] SBU and the mononuclear [Cu(HSuc)2(Hpz)4] complex were also obtained [21]. 

Isocitrate lyase catalyzes the following reaction isocitrate ion — glyoxylate ion + succinate ion... 

Urea possesses negligible basic properties (Kb = 1.5 x 10 l4), is soluble in water and its hydrolysis rate can be easily controlled. It hydrolyses rapidly at 90-100 °C, and hydrolysis can be quickly terminated at a desired pH by cooling the reaction mixture to room temperature. The use of a hydrolytic reagent alone does not result in the formation of a compact precipitate the physical character of the precipitate will be very much affected by the presence of certain anions. Thus in the precipitation of aluminium by the urea process, a dense precipitate is obtained in the presence of succinate, sulphate, formate, oxalate, and benzoate ions, but not in the presence of chloride, chlorate, perchlorate, nitrate, sulphate, chromate, and acetate ions. The preferred anion for the precipitation of aluminium is succinate. It would appear that the main function of the suitable anion is the formation of a basic salt which seems responsible for the production of a compact precipitate. The pH of the initial solution must be appropriately adjusted. 

A variety of reagents could be used to carry out such a conversion (18,19). We chose to react the alkoxide ion with succinic anhydride (SA), because the alkoxide ion could be converted quantitatively to the carboxylate ion when excess of SA is used, and also because no side reactions are reported (19). The carboxylate anion, 3, thus formed was used to polymerize PVL giving the masked poly(oxyethylene)-b-po y(pivalolactone) co-polymeric salt, 4. The salt, 4, was converted to the teiechelomer, 5, by acid hydrolysis.. ... 

A series of experiments was conducted to form monoethyl and diethyl succinate using either sulfuric acid or acidic ion-exchange resin as catalysts. The esterification of succinic acid is modeled as a simple series reaction sequence. 

Electroless Ni-Ge-P was studied as a model system for ternary alloy deposition [112], A chloride-free solution with GeC>2 as a source of Ge, hypophosphite as reducing agent, aspartic acid as a selective complexant for Ni2+ ions, which was operated at 80 °C in the pH range of 5-5.8, was developed for depositing Ni-Ge-P films with a tunable Ge content from 0 to 25+ at%. The use of a complexant such as citric acid, which complexed Ge(IY) ions as well as Ni2+ ions, resulted in a much lower Ge content in the electroless deposit, and a more complicated solution to study for the reasons discussed above. The aspartate-containing electroless solution, with its non-complexing pH buffer (succinic acid), approximated a modular system, and, with the exception of the aspartic acid - Ni2+ complexation reaction, exhibited a minimum level of interactions in solution. 

This enzyme [EC 1.14.11.1], also known as y-butyrobe-taine, 2-ketoglutarate dioxygenase, catalyzes the reaction of 4-trimethylammoniobutanoate with S-keto-glutarate (or, 2-oxoglutarate) and dioxygen to yield 3-hydroxy-4-trimethylammoniobutanoate, succinate, and carbon dioxide. Both iron ions and ascorbate are needed as cofactors. 

The neutral carboxyl group is not very effective in increasing the reduction rate of the complex. However, when the proton is removed from the carboxyl, the effect can increase and is greatest when the carboxyl ion is in a configuration favorable to chelation. Thus, the inverse (H+) path is not even observable for acid succinate in the same acidity range as that for which this path is important in the acid malonato reaction. The acid dissociation constants are known well enough so that the behavior difference between acid malonato and acid succinato can not be entirely ascribed to different acidities of the complexes. The results obtained with the acid malonate complexes, as reported in Table II, incidentally provide no support for the hypothesis (22) that electron transfer takes place by remote attack across hydrogen bonds. 

The oxygen reactivity of flavohydroquinone bound to apoflavoprotein dehydrogenases can vary considerably from fast (flavodoxins), moderate (xanthine oxidase) to nil (succinate dehydrogenase) Most, but not all, flavoprotein dehydrogenases contain one or more types of metal prosthetic groups, e.g. xanthine oxidase contains also Fe and Mo. Since these metal ions are involved in electron flux, their possible participation in the reaction with O2 cannot be excluded. Much evidence, however, indicates that the flavin is involved in the one-electron reduction of Oj, as shown in Equation (5). 

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