Lactic acid and lactate

Picataggio, S. K., Zhang, M., Franden, M. A., and Franden, M. J. D. 1998. Recombinant lactobacillus for fermentation of xylose to lactic acid and lactate. United States Patent 5798237. 

The inhibition of cytochrome c oxidase, and resultant disturbance of electron transport, results in decreased mitochondrial O2 utilization and decreased ATP (Olsen and Klein, 1947). Anaerobic metabolism leads to an accumulation of lactic acid and lactate acidosis, and the combination of lactate acidosis and cytotoxic hypoxia causes severe metabolic disturbances, particularly in the central nervous system (CNS), resulting in disturbances of perception and consciousness. 

PROBLEM 3.5 Calculate the ratio of lactic acid and lactate required in a buffer system of pH 5.00. The p fa of lactic acid is 3.86. Solution The equation, . .T,, [lactate] P P a °g [lactic acid] can be rearranged to, [lactate] TT ° [lactic acid] a = 5.00 - 3.86 = 1.14 Therefore the required ratio is [lactic acid] - mtllo6 L14 = 13.8 For a lactate buffer to have a pH of 5, the lactate and lactic acid components must be present in a ratio of 13.8 to 1. Because a good buffer contains a mixture of a weak acid and its conjugate base present in near equal concentrations and when the buffered pH is within 1 pH unit of the pK lactate buffer is a poor choice in this situation. A better choice would be the acetate buffer. 

Holmen RE (1958) Acrylates by catalytic dehydratirai of lactic acid and lactates. US Patent 2,859,240... 

The patient in intensive care with lactic acidosis pH 7.15, has an arterial blood lactate of 5.4 mmol/l. What s the difference between lactic acid and lactate ... 

Biologically important compounds. Again, mostly nondeterminable at common CPEs are most of amino acids glucose (typically, via the H2O2 release and its subsequent oxidation or reduction in the ampero-metric mode see [180] and Figure 11.4d) and other monosaccharides less-frequent vitamins (A, Bl, B9, B12, D, Kl, and K3), hormones, and steroids lactic acid and lactates and antioxidants (mainly flavanols and flavonoids), plus some bacteria and viruses. 

Besides the classical Si and Al-containing zeolites, there is an ongoing search toward other Lewis acidic zeolites and other microporous materials suitable for this reaction. Taaming et al. made a comparison between beta zeolites substituted with Al, Sn, Zr, and Tl. As with the homogeneous catalysts, this comparison pointed to Sn-based catalysts as extremely selective for this reaction. The authors obtained lactic acid and lactate yields of 90% and >99% at 125 and 80°C, respectively, with an Si Sn ratio of 125 [67]. Since then, numerous reports were published including Sn-montmorillonite [68], mesoporous Sn-MCM-41 (Mobil Composition of Matter) [69,70], Sn-MFI (Mordenite Framework Inverted) [70,71], Sn-deAl-beta [72], Sn-SBA-15 (Santa Barbara Amorphous type material) [70], Sn-MWW (Zeolite Framework Type M-22)... 

Sequestrants form complexes with metal ions, which accelerate oxidative degradation, and show synergistic effects with the a.m. antioxidants. - Phytic acid, calcium gluconate (- gluconic acid), - lactic acid and lactates, - tartaric acid and tartrates, - citric acid and citrates and - lecithin are such RR-based products. 

Acetaldehyde Cyanohydrin. This cyanohydrin, commonly known as lactonitnle, is soluble in water and alcohol, but insoluble in diethyl ether and carbon disulfide. Lactonitnle is used chiefly to manufacture lactic acid and its derivatives, primarily ethyl lactate. Lactonitnle [78-97-7] is manufactured from equimolar amounts of acetaldehyde and hydrogen cyanide containing 1.5% of 20% NaOH at —10 20 ° C. The product is stabili2ed with sulfuric acid (28). Sulfuric acid hydroly2es the nitrile to give a mixture of lactic acid [598-82-3] and ammonium bisulfate. 

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. 

What is true for acetic acid is also true for other carboxylic acids at the ph ysiological pH that exists inside cells, carboxylic acids are almost entirely dissociated. To reflect this fact, we always refer to cellular carboxylic acids by the name of their anion—acetate, lactate, citrate, and so forth, rather than acetic acid, lactic acid, and citric acid. 

Notice in Example 141(a) that the total volume of solution is irrelevant All that is required to solve for [H+] is the number of moles of lactic acid and sodium lactate. The pH of the buffer is 3.85 whether the volume of solution is 550 mL, 1 L, or even 10 L. This explains why diluting a buffer with water does not change the pH. 

A solution of equal concentrations of lactic acid and sodium lactate was found to have pH = 3.08. (a) What are the values of pK, and K, of lactic acid (b) What would the pH be if the acid had twice the concentration of the salt ... 

Choi and Won (1999) have reported a very u.seful strategy of recovering relatively nonvolatile lactic acid (e.g. from fermentation of carbohydrates) as volatile methyl lactate using a cationic ion-exchange resin as the catalyst. In another column reactor the methyl lactate is hydrolysed, using a cationic ion-exchange resin as the catalyst, to lactic acid and methanol, and the latter is recycled. 

Therefore, the overall kinetic rate expression for ethyl lactate conversion from lactic acid and ethanol can be given by ... 

Chu CL, Spiess WEL and Wolf W (1992) Diffusion of lactic acid and Na-lactate in a protein matrix. Food Sci Technol 25, 476-481. 

Lactic acid The normal concentration of lactate in the blood is about 1 mmol/L which is the balance between production and utilisation. Various tissues produce lactic acid and release it into the blood, from where it is taken up by liver and converted to glucose (or glycogen) (the Cori cycle, see above). 

Lactose is readily fermented by lactic acid bacteria, especially Lactococcus spp. and Lactobacillus spp., to lactic acid, and by some species of yeast, e.g. Kluyveromyces spp., to ethanol (Figure 2.27). Lactic acid may be used as a food acidulant, as a component in the manufacture of plastics, or converted to ammonium lactate as a source of nitrogen for animal nutrition. It can be converted to propionic acid, which has many food applications, by Propionibacterium spp. Potable ethanol is being produced commercially from lactose in whey or UF permeate. The ethanol may also be used for industrial purposes or as a fuel but is probably not cost-competitive with ethanol produced by fermentation of sucrose or chemically. The ethanol may also be oxidized to acetic acid. The mother liquor remaining from the production of lactic acid or ethanol may be subjected to anaerobic digestion with the production of methane (CH4) for use as a fuel several such plants are in commercial use. 

In the Korkes and Ochoa (11) mechanism proposed for the malo-lactic reaction (see top of next page), pyruvic acid is either a short-lived, fleeting intermediate, or it is bound to malic enzyme so that as soon as it is formed by the enzyme, it is converted to lactic acid by lactate dehydrogenase. [Both malic enzyme ( malic ) and malate dehydrogenase (de-... 

Burton, L. V. 1937B. Part II. Conversion of calcium lactate to lactic acid and production of whey powders. Food Ind. 9, 634-636. 

A requirement for all fermentations is the existence of a mechanism for coupling ATP synthesis to the fermentation reactions. In the lactic acid and ethanol fermentations this coupling mechanism consists of the formation of the intermediate 1,3-bisphosphoglycerate by the glyceraldehyde 3-phosphate dehydrogenase (Fig. 10-3, step a). This intermediate contains parts of both the products ATP and lactate or ethanol. 

If we convert (+)-lactic acid into its methyl ester, we can be reasonably certain that the ester will be related in configuration to the acid, because esterification should not affect the configuration about the chiral carbon atom. It happens that the methyl ester so obtained is levorotatory, so we know that (+)-lactic acid and (—)-methyl lactate have the same relative configuration at the asymmetric carbon, even if they possess opposite signs of optical rotation. However, we still do not know the absolute configuration that is, we are unable to tell which of the two possible configurations of lactic acid, 2a or 2b,... 

A solution of equal concentrations of lactic acid and sodium lactate was found to have pH = 3.08. 

A 37-year-old HIV-infected woman receiving stavudine, lamivudine, and indinavir developed epigastric pain, anorexia, and vomiting. She had lactic acidosis (serum lactate 4.9 mmol/1), raised liver enzymes, and an increased prothrombin time. She had hepatomegaly and tachypnea and required mechanical ventilation. Her progress was complicated by pancreatitis and acute respiratory distress syndrome. Antiviral medication was stopped and she was treated with co-enzyme Q, carnitine, and vitamin C. The serum lactic acid and transaminases returned to normal over 4 weeks and she was weaned off the ventilator after 4 months. 

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