Trichloroacetic acid, 293 Table

An electronegative substituent particularly if it is attached to the a carbon increases the acidity of a carboxylic acid As the data m Table 19 2 show all the mono haloacetic acids are about 100 times more acidic than acetic acid Multiple halogen sub stitution increases the acidity even more trichloroacetic acid is 7000 times more acidic than acetic acid ... 

Trichloroacetic acid [76-03-9] (Cl CCOOH), mol wt 163.39, C2H01 02, forms white dehquescent crystals and has a characteristic odor. Physical properties are given in Table 3. 

Fraction Fla was chosen for structural purposes due to its better solubility in water and the absence of Xyl. In order to remove noncovalently associated protein, fraction Flap was submitted to sequential shaking cycles with a mixture of chloroform-buthanol, as indicated by Sevag and described by Staub [17]. The fraction was also treated with trichloroacetic acid. In both procedures, coprecipitation of carbohydrate and protein was observed, suggesting strong linkages and a more complex structure. Fla as was submitted to mild acid hydrolysis yielding Flas and Flap (Table VI). 

Experiments conducted with the tobacco hornworm, Manduca sexta and the aquatic plant, Lemna minor are consistent in finding that canavanine does not affect whole organism ability to incorporate [ Hjleucine into trichloroacetic acid-insoluble materials (see Table I). Such determinations evaluate the balance between reactions fostering protein synthesis and those responsible for the turnover and degradation of proteins. If the treatment time is reduced to 30 min, so as to accentuate synthetic reactions over those of catabolism, the result is the same. 

Studies of canavanine interaction with the tobacco hornworm and J-. miTior also revealed the marked ability of canavanine.to inhibit whole organism incorporation of [ Hjthymidine and uridine into trichloroacetic acid-precipitated materials. When canavanine is provided simultaneously with the appropriate radio-labeled precursor, ample evidence for curtailed nucleic acid metabolism emerges but protein synthesis is unaffected (Table I, exp. I). In experiment II, canavanine is allowed to assimilate... 

As shown in the table below (Fig. 3.20), acidity gets stronger as acetic acid changes to trichloroacetic acid, which is a major corrosive and a very damaging acid. More chlorine atoms mean more acidity. 

A large number of N-containing compounds of low molecular weight are not precipitated with proteins by 12% trichloroacetic acid. Some small peptides are included in this group. These nonprotein nitrogen (NPN) constituents aggregate about 1 g/liter and account for about 6% of the total N (i.e., 250-350 mg of N per liter). The principal NPN components are listed in Table 1.6 (Wolfschoon-Pombo and Kloster-meyer 1981). The wide variations in concentrations that have been reported for these constituents probably arise from the fact that many of them are metabolites of amino acids and nucleic acids and from the fact that their concentrations in milk depend on the amounts of those substances consumed by the cow. 

The lower the value of Ka, the higher the value of pKa. In other words, the higher the value of pKa, the weaker the acid. For example, the pKa of trichloroacetic acid is 0.5, whereas that of acetic acid, a much weaker acid, is nearly 5. Similar remarks apply to bases the higher the value of pKh, the weaker the base. Values of pKa and pKh are included in Tables 10.1 and 10.2. 

Table V.5 Crystal field effect in molecular compounds of trichloroacetic acid with ethers, aldehydes etc.and of some salts of the trichloroacetic acid. A( SC1) <0.7 MHz in the compounds TCA-X A (3SC1) K 1.6 MHz in the salts...

The determination of amino acid composition has been performed in hydrolysates of adrenodoxin in 6 N-HC1 at 110° C for various periods after the removal of iron from adrenodoxin by trichloroacetic acid precipitation or by a, a -dipyridyl treatment. The tentative amino acid composition is proposed to be as shown in Table 3. Adrenodoxin contains about 100 amino acid residues with an abundance of aspartic and glutamic acids, which may account for the strong affinity of adrenodoxin for... 

We shall present our findings on the chemical nature of so-called labile sulfur in adrenodoxin. (1) The determination of dehydroalanine formation gives a negative result in measuring pyruvate after mild acid hydrolysis of trichloroacetic acid precipitates of adrenodoxin (Table 12). 

There are a number of factors that determine whether a protonic acid can initiate polymerization of alkenes. Their acidity (pKa), and therefore the basicity of the resulting counteranion, determines the efficiency of initiation. Although reliable pKa values of acids stronger than sulfuric or hy-droiodic (pKa < -9) are difficult to obtain in aqueous solutions due to their nearly complete dissociation, the pKa values of acetic acid (4.75) and trichloroacetic acid (0.7) in water provide useful references. Conductometric and potentiometric estimates of the pK values of selected protonic acids in various organic solvents are summarized in Table 11 in descending acid strength. These values are not very precise, however, because the amount of moisture in each system was not monitored precisely. 

When 1.5 volumes acetone is added to the trichloroacetic acid filtrate of the gastric juice, an abundant flocculent precipitate forms, which contains all the components of dissolved mucin with the exception of soluble mucus. If this precipitate is taken up in dilute alkali and then acidified with dilute HCl down to pH 3.5, a fine flocculent precipitate forms, which we named dissolved mucoprotein (G27, G36). It was later renamed glandular mucoprotein (G9, G38) because of its close relationship to the fundic glands of the stomach. This material contained much protein its nitrogen content was 12.61 0.44% and its tyrosine content 7.50 0.65% by the Folin-Giocalteu reaction. The reducing substance content was 6.38 1.48% before and 12.5% after hydrolysis (G9, G27, G36) (see Table 4). Werner (W9) determined the composition of this mucoprotein fraction and found that it contained 11.2% N by Kjeldahl, 8.8% hexosamine, 4.8% uronic acid, and 2.0% sialic acid. 

Table 59 presents activation parameters for the decarboxylation of trichloroacetic acid in various basic solvents. Presumably the acid is in the form of its anion in these solvents. The activation parameters fall into a fairly narrow range and the differences presumably represent specific solvation effects. In an acidic solvent, decanoic acid, the activation parameters for the decomposition of potassium trichloroacetate are increased considerably. The values are A/f = 41.4 kcal.mole" and A5 = 27.7 eu . The activation parameters presumably reflect a composite of a prior equilibrium between decanoic acid and the trichloroacetate anion along with decarboxylation of the latter anion. The rate of decarboxylation of sodium nitroacetate is about five times faster in methanol than in water . This effect was attributed to dispersion of the negative charge at the transition state , a process which is more favorable in the less polar methanol solvent. Similarly, the decar-... 

The addition of the 5-pentanoate radical from methyl adipate to butadiene has been intensively investigated, because in this way long chain l,n-diacids are easily accessible a total yield of 96% has been claimed for this reaction (Table 8, entry 7). Different Kolbe radicals from acetic acid, monochloroacetic acid, trichloroacetic acid, oxalic acid, methyl adipate and methyl glutarate have been added to ethylene, propylene, fluoroalkenes and dimethyl maleate. In this detailed study the influence of current density, alkene type and alkene concentration on the product yields and product ratios have been discussed. 

Recently, a method allowing detection of a high quantity of proteins with the proteomic approach has been developed (Sarry et al., 2004). In this method, a solution containing 12.5% of trichloroacetic acid (TCA) in cold acetone and a reducing agent is used (Table 7.2). Using this approach only proteins in the pulp are extracted, and enzymes potentially involved in protein modification are inhibited. 

Instead of purified SpA, fixed SpA-bearing bacteria (Table 3.3) can also be used as immunosorbent (Sections 7.1.8.1 and 13.5.2). Binding by 1 ml of a 10% suspension is about 1.2-1.6 mg IgG (of the proper species). Fixation of bacteria with trichloroacetic acid instead of formalin may offer some advantages (Section 13.5.2). 

SpA-containing Staphylococci (Section 3.3), fixed with trichloroacetic acid (TCA) or formalin (Section 3.3.1), may also serve as immunosorbent for many mammalian antibodies (Table 7.1). Both fixation procedures are satisfactory but yield products with different properties. Fixation of Staphylococci with hot TCA (Lindmark, 1982) removes the negatively charged cell-wall polymer teichoic acid, producing an IgG-sorbent which can bind 1.4 mg human IgG per ml of a 10% (v/v) suspension of bacteria and is stable for about 5 months. Formalin-fixed bacteria (Kessler, 1976) bind 35% more IgG and are stable for at least 1 year. However, IgG can be eluted quantitatively from TCA-fixed bacteria but not from formalin-fixed bacteria, probably due to the interaction between IgG and teichoic acid, unless 80 mM MgCh is included in the acid buffer. 

GF/C). When the filter is dry, it is swirled using blunt-end forceps in a beaker containing 200 ml of ice-cold 5% trichloroacetic acid (TCA) and 20 mM sodium pyrophosphate for 2 min (repeated three times in a new solution). The filter is then dipped for 2 min in 70% ethanol and dried. The incorporated radioactivity can now be measured with a scintillation counter. If 1 ng of DNA was spotted, then 0.5-10 X 10 cpm should be expected. By comparing with the cpm obtained from the original sample, directly spotted and not washed, the efficiency of incorporation can be calculated (Table 7.15). 

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