Protein trichloroacetic acid

Tetrabutylammonium chloride TATA-binding protein telomere-binding protein Trichloroacetic acid tricarboxylic acid T-cell receptor... 

Precipitation of Proteins. Proteins can be precipitated from solution in various W ays. Irreversible denaturation is of interest only for the total analysis of pre-cipitable protein (trichloroacetic acid or uranyl acetate being used) or for removal... 

Trichloroacetic Acid (TCA) causes precipitation of proteins and coagulative necrosis of epidermal cells [4]. The extent of damage is indeed concentration dependent. Concentrations range from 10 to 50%. Superficial TCA peeling is induced by concentrations of 10-30% whereas higher concentrations cause medium depth or deep peeling. The combination of salicylic acid followed by TCA 10-15% induces superficial wounding. 

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). 

Exudate collection in trap solutions usually requires subsequent concentration steps (vacuum evaporation, lyophilization) due to the low concentration of exudate compounds. Depending on the composition of the trap solution, the reduction of sample volume can lead to high salt concentrations, which may interfere with subsequent analysis or may even cause irreversible precipitation of certain exudate compounds (e.g., Ca-citrate, Ca-oxalate, proteins). Therefore, if possible, removal of interfering salts by use of ion exchange resins prior to sample concentration is recommended. Alternatively, solid-phase extraction techniques may be employed for enrichment of exudate compounds from the diluted trap solution (11,22). High-molecular-weight compounds may be concentrated by precipitation with organic solvents [methanol, ethanol, acetone 80% (v/v) for polysaccharides and proteins] or acidification [trichloroacetic acid 10% (w/v), per-... 

Webb et al. [56] determined free penicillamine in the plasma of rheumatoid arthritis patients. Plasma ultrafiltrate was mixed with trichloroacetic acid and 4-aminobenzoic acid as internal standards, and HPLC mobile phase to determine total reduced penicillamine. Plasma was vortexed with trichloroacetic acid, the precipitated protein was removed after 15 min by centrifuging, and the supernatant solution was filtered and mixed with 4-aminobenzoic acid. In each instance, a 50-pL portion of solution was analyzed on a 25-cm column of Spherisorb-NH2 (5 pm) at 25 °C, with an electrochemical detector having dual porous graphite electrodes set at... 

Bergstrom et al. [63] used HPLC for determination of penicillamine in body fluids. Proteins were precipitated from plasma and hemolyzed blood with trichloroacetic acid and metaphosphoric acid, respectively, and, after centrifugation, the supernatant solution was injected into the HPLC system via a 20-pL loop valve. Urine samples were directly injected after dilution with 0.4 M citric acid. Two columns (5 cm x 0.41 cm and 30 cm x 0.41 cm) packed with Zipax SCX (30 pm) were used as the guard and analytical columns, respectively. The mobile phase (2.5 mL/min) was deoxygenated 0.03 M citric acid-0.01 M Na2HP04 buffer, and use was made of an electrochemical detector equipped with a three-electrode thin-layer cell. The method was selective and sensitive for mercapto-compounds. Recoveries of penicillamine averaged 101% from plasma and 107% from urine, with coefficients of variation equal to 3.68 and 4.25%, respectively. The limits of detection for penicillamine were 0.5 pm and 3 pm in plasma and in urine, respectively. This method is selective and sensitive for sulfhydryl compounds. 

To determine the optimal reaction time for a particular radioiodination, 5 pi aliquots of the reaction medium can be removed every 30 seconds, diluted 1 20,000 with 20 mM Tris, 1 mM ethylenediaminetetraacetic acid (EDTA), pH 7.4, containing 0.5 mg/ml BSA as a carrier protein. Finally, precipitate a small amount of the diluted aliquot with trichloroacetic acid (TCA, 60 percent), centrifuge to recover the pellet, wash the pellet once with TCA, and measure the amount of radioactivity in the pellet and supernatant using a gamma counter. The reaction period representing optimal radiolabel incorporation should be used for subsequent radioiodinations. 

Bradford reagent contains the dye Coomassie blue G-250 in an acidic solution. The dye binds to protein, yielding a blue colour that absorbs maximally at 595 nm Copper-containing reagent that, when reduced by protein, reacts with bicinchonic acid yielding a complex that displays an absorbance maximum at 562 nm Essentially involves initial precipitation of protein out of solution by addition of trichloroacetic acid. The protein precipitate is redissolved in NaOH and the Lowry method of protein determination is then performed Interaction of silver with protein - very sensitive method... 

Savory et al. 3S) measured calcium and magnesium directly in protein-free filtrates of serum or urine. Baker et al. 36) found that both trichloroacetic acid and hydrochloric acid suppress calcium absorption and that uniform acid content is therefore required for the determination of calcium. Okuda and Sasamoto37) determined calcium by adjusting solution conditions to 20 — 50 % methanol and 650 mg % lanthanum serum is diluted 21-fold and urine is diluted 10—21 fold to bring the calcium concentration into the optimum range of 1 to 0.5 mg %. 

More recent determinations of serum iron have been reported by Schmidt 57), who simply diluted with lanthanum chloride solution, and by Tavenier and Hellen-doorn58), who deproteinized samples in the latter study, iron in the protein precipitate is analyzed to correct the serum iron level. Uny etal. 59) determined serum iron, using ultrasonic nebulization of the sample to increase the sensitivity. Olson and Hamlin 6°) have determined serum iron and total iron-binding capacity. Proteins are precipitated and iron (III) is released by heating with trichloroacetic acid. 

The most efficient precipitants for protein removal were zinc sulfate, acetonitrile, and trichloroacetic acid (at 2 1 volume of precipitant to plasma, the protein removal values were, respectively, 96, 92, and 91% with <1% RSD for n = 5). 

Maltose, the endproduct of amylase activity, was measured by the method of Dahlquist (16). 3Peptide=supernatant protein which was not precipitated when trichloroacetic acid (TCA) solution was added to 5% TCA (W/V) (17). 

Two further compounds are briefly discussed here. Tetrachloroethylene administered to animals yielded 2,2,2-trichloroacetic acid (10.95, Fig. 10.23) as the only chlorinated metabolite [13]. These findings provided the first evidence that tetrachloroethylene is oxidized by cytochrome P450 to its epoxide (10.94), which rearranges by Cl migration to 2,2,2-trichloroacetyl chloride (Fig. 10.23). The latter hydrolyzes to 2,2,2-trichloroacetic acid (10.95), but also acylates tissue proteins, a reaction of unclear toxicological significance. In vitro investigations of tetrachloroethylene oxide (2,2,3,3-tetrachlo-rooxirane, 10.94) further showed that it hydrolyzes to the vicinal diol (10.96... 

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