Lactate reaction

Earle and coworkers [54] have performed Diels-Alder reactions in neutral ionic liquids. The results of reactions of cyclopentadiene with dimethyl maleate, ethyl acrylate and acrylonitrile are reported in Table 6.10. The cycloadditions proceeded at room temperature in all of the ionic liquids tested, except [BMIMJPF4, and gave almost quantitative yields after 18-24h. The endo/exo selectivity depends on dienophile. No enantioselectivity was observed in the [BMIM] lactate reaction. 

Metal lactate, reaction with an alkyl halide, 24 118... 

In Fig. 24 we plot various distances that reveal a compression of several residues that occurs close to the reaction event. These are taken from a trajectory with a concerted hydride and proton transfer. All graphs are plotted in the pyruvate to lactate reaction direction. 

Concerted vs. stepwise transfers. We now address the question of whether the hydride and proton transfers are concerted, or whether the hydride transfer precedes the proton in the pyruvate to lactate reaction direction. Our TPS study showed that both mechanisms are possible. In Fig. 25 we show the distribution of the time lag between the hydride and proton transfer for all reactive trajectories. We note that both concerted and sequential transfers are possible, and that 74% of the trajectories have a time lag greater than 10 fs, indicating that the majority of reactive trajectories have sequential transfer steps. 

Figure 9.12. Enzyme-wide changes during transition from reactant to product. Exemplary critical distance shifts during the interconversion of pyruvate and lactate by lactate dehydrogenase. Reading the graph from left to right, the pyruvate to lactate reaction direction, the reaction occurs slightly after the minimum hydride donor-acceptor distance. Distances are plotted every 1 fs over a 7.3 ps...

The lag phase is the time for the enzymatic reaction to reach maximum velocity the latter is the rate that is zero-order in substrate, and substrate-saturation kinetics are assumed. At the beginning of the reaction, changes in concentration of the substrate are assumed to be trivial, and the substrate is present in large excess. The lag phase depends on the specimens activity and the complexity of the reaction scheme being used. For example, the determination of LD with the pyruvate-to-lactate reaction has little or no lag phase, even with serum specimens having low activity ... 

In most biochemical reactions the pH of the medium is close to 7 At this pH car boxylic acids are nearly completely converted to their conjugate bases Thus it is common practice m biological chemistry to specify the derived carboxylate anion rather than the carboxylic acid itself For example we say that glycolysis leads to lactate by way of pyruvate... 

Biochemical oxidation of lactate to pymvate by lactate dehydrogenase is a well-known enzymatic reaction ia metaboHc pathways. 

Reaction of a metal lactate (such as silver lactate) with an alkyl haUde is a classic method of preparation of the ester, but it is too expensive to be of commercial relevance. Lactamide [2043-43-8] is another high yielding condensation product from lactic acid. It can be produced by aminolysis of dilactide or lactate ester such as methyl or ethyl lactate. 

The absorbance change (AM) at 340 nm can be used to determine the amount of pymvate remaining. The lactate dehydrogenase [9001-60-9] catalyzed reaction can also be used in the reverse direction to measure lactate. The reaction takes place in a buffer of pH 9—10 that neutralizes Hberated H". ... 

OC-Hydroxycarboxylic Acid Complexes. Water-soluble titanium lactate complexes can be prepared by reactions of an aqueous solution of a titanium salt, such as TiCl, titanyl sulfate, or titanyl nitrate, with calcium, strontium, or barium lactate. The insoluble metal sulfate is filtered off and the filtrate neutralized using an alkaline metal hydroxide or carbonate, ammonium hydroxide, amine, or alkanolamine (78,79). Similar solutions of titanium lactate, malate, tartrate, and citrate can be produced by hydrolyzation of titanium salts, such as TiCl, in strongly (>pH 10) alkaline water isolation of the... 

The penicillins in general, ate renowned for their lack of toxicity. The most common adverse effect of the use of penicillins is an allergic reaction which can change from a mild rash to fatal anaphylactic shock in rate cases. AH penicillins cross the placenta and ate excreted in maternal milk. However, the relative freedom from toxicity tenders these compounds valuable agents during pregnancy and lactation. 

Several other biosensors have been developed usiag this oxygen-quenched fluorescence approach. Target species iaclude ethanol [64-17-5] hydrogen peroxide [7722-84-17, H2O2, lactate, and xanthine [69-89-6] C H4N402, usiag alcohol oxidase, catalase [9001-05-2] lactate oxidase, and xanthine oxidase, respectively. An additional technique for biocatalytic biosensors iavolves the firefly chemiluminescent reaction (17) ... 

Salts of Organic Acids. Calcium salts of organic acids may be prepared by reaction of the carbonate hydroxide and the organic acid (9). Calcium lactate [814-80-2] is an iatermediate ia the purification of lactic acid from fermentation of molasses. Calcium soaps, soaps of fatty acids, ate soluble ia hydrocarbons, and are useful as waterproofing agents and constituents of greases (9). 

Medium Boiling Esters. Esterificatioa of ethyl and propyl alcohols, ethylene glycol, and glycerol with various acids, eg, chloro- or bromoacetic, or pymvic, by the use of a third component such as bensene, toluene, hexane, cyclohexane, or carbon tetrachloride to remove the water produced is quite common. Bensene has been used as a co-solvent ia the preparatioa of methyl pymvate from pymvic acid (101). The preparatioa of ethyl lactate is described as an example of the general procedure (102). A mixture of 1 mol 80% lactic acid and 2.3 mol 95% ethyl alcohol is added to a volume of benzene equal to half that of the alcohol (ca 43 mL), and the resulting mixture is refluxed for several hours. When distilled, the overhead condensate separates iato layers. The lower layer is extracted to recover the benzene and alcohol, and the water is discarded. The upper layer is returned to the column for reflux. After all the water is removed from the reaction mixture, the excess of alcohol and benzene is removed by distillation, and the ester is fractionated to isolate the pure ester. 

Some alcohols that have been converted into the corresponding fluorides by reactions with diethyldminosulfur trifluoride include 1-octanol, 2-methyl-2-butanol, isobutyl alcohol, cyclooctanol, ethylene glycol, crotyl alcohol, 2-phenylethanol, 2-bromoethanol, ethyl lactate, and ethyl a-hydrox3maphthaleneacetate. ... 

FIGURE 19.30 (a) Pyruvate reduction to ethanol in yeast provides a means for regenerating NAD consumed in the glyceraldehyde-3-P dehydrogenase reaction, (b) In oxygen-depleted muscle, NAD is regenerated in the lactate dehydrogenase reaction. 

One of the standard methods for construction of the basic heterocyclic ring was elaborated not long after the turn of the century. Thus, condensation of ethyl lactate with guanidine leads to the imine of the desired ring system (47), possibly by a reaction scheme such as that outlined below. Hydrolysis affords the oxazolidinedione (48). Methylation in the presence of base gives 49. 

Slime-Forming Bacteria. Several forms of bacteria produce a slimy capsule under certain environmental conditions. These organisms are heterotrophic, that is, they obtain their energy from organic sources such as sodium lactate. The reaction is... 

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