Precipitation, myoglobins

Transfer precipitated myoglobin to dialysis tubing and dialyze against dialysis buffer (1 vol protein 10 vol buffer) for 24 hr at 4°C, changing buffer every 8 hr. 

Denaturation horse heart cytochrome Denaturation whale myoglobin Denaturation a-chymotrypsinogen Precipitation sheep liver nucleoprotein at 40°C in 30 minutes... 

For a given protein, the distribution curves for different values of Co are all determined by the same differential curve. Co merely determines the point of entry to the curve. Taking the case of two solutions of carboxy-myoglobin, one containing 30 gm per liter and the other being a tenfold dilution of this, we read off from Fig. 5 the respective salt concentrations for first precipitation (points A and B) and transfer them to Fig. 6. The two distribution curves of the precipitation will now be portions A to C and B to C of the differential curve in Fig. 6 for the stronger and weaker solutions respectively. The two peaks represented by the areas AA C and BB C are of course of different sizes because of the different amounts of protein taken, but if they are normalized by expressing the amounts as... 

In five experiments iodination efficiency 40-44% 50-80% of 1 incorporated 90% of myoglobin precipitated with excess antibody... 

Treatment for sympathomimetic amine overdose involves general supportive measures. Acid diuresis wiU enhance the elimination of the amphetamines, but its use is con-troversiaT and is certainly not without the risk of renal failure from precipitation of myoglobin (enhanced at acid pH) in renal tubules (myoglobinuria is the result of rhabdomyolysis). 

Due to precipitation of myoglobin and oxalate crystals in the renal tubules. 

Dense gas antisolvent techniques are amenable to the precipitation of proteins because of the low solubility of these compounds in DGs such as carbon dioxide. Lysozyme, trypsin, myoglobin, and insulin are examples of peptides that have been precipitated from organic solutions using CO2 as an antisolvent. Both batch and semicontinuous DG antisolvent techniques have been used to precipitate proteins from organic solvents such as methanol, ethanol, and dimethyl sulfoxide. ... 

Similar experiments were performed on solutions of avidin and BSA (both 10 6 M) and avidin, BSA, and lysozyme (all 10 M). In the avidin/BSA system, a total of 77% of the original avidin was recovered in resolubilized precipitate, while in the avidin/BSA/lysozyme system, 87% of the original avidin was recovered in resolubilized precipitate. As a control, solutions of myoglobin in buffer (10" M), BSA in buffer (10" M), and BSA plus lysozyme in buffer (both 10 M) were mixed with concentrated surfactant solution to obtain a mixture concentration of 4 x 10 M DMPE-B and 7.5 x 10 5 m C12E8. In each case, no turbidity developed in the solution and no precipitate was obtained upon prolonged centrifugation. Thus, it appears that precipitation is completely restricted to avidin, the protein to which the affinity phospholipid binds specifically. 

Figure 9. Continued, (c) Ultraviolet—visible spectrum of the supernatant after affinity precipitation of avidin from an avidin—myoglobin solution (both 10" M in 0.2 M ammonium carbonate buffer at pH 8.9) by a DMPE-B-C12E8 solution. The supernatant was sampled after precipitation for two hours and centrifugation at 5000 rpm for twenty minutes, (d) Ultraviolet—visible spectrum of avidin—DMPE-B precipitate described in text and caption 9(c) after resuspension in 10" M C12E8 solution in 0.2 M ammonium carbonate buffer at pH 8.9.

A detailed study by Thiering et al. (102) considered a number of proteins, solvents, and solvent mixtures (Table 3). Insulin was precipitated using SCF CO2 from DMSO, ethyl acetate, methanol, and ethanol. The particle size ranged between 0.05 and 1.8 pm. Insulin precipitated from solvents in which the solubility of insulin was low (ethyl acetate, methanol, ethanol) had a smaller particle size than insulin precipitated from solvents with a higher insulin solubility (DMSO). Polydisperse particles of myoglobin were precipitated from DMSO solutions (mean particle sizes of 0.03 pm and 0.4 pm), whereas monodisperse myoglobin particles were precipitated from a methanol solution (0.05-0.3 pm). 

B. Complications. Myoglobin released by damaged muscle cells may precipitate in the kidneys, causing acute tubular necrosis and renal failure. This is more likely when the semm CPK level exceeds several thousand lU/L and if the patient is dehydrated. With severe rhabdomyolysis, hyperkalemia, hyperphosphatemia, hypemricemia, and hypocalcemia may also occur. 

G. Renal failure. Examples of dmgs and toxins causing renal failure are listed in Table I-28. Renal failure may be caused by a direct nephrotoxic action of the poison or acute massive tubular precipitation of myoglobin (rhabdomyolysis), hemoglobin (hemolysis), or calcium oxalate crystals (ethylene glycol) or it may be secondary to shock caused by blood or fluid loss or cardiovascular collapse. 

B. To produce urinary aikaiinization, to enhance elimination of certain acidic drugs (salicylate, phenobarbital, chlorpropamide, chiorophenoxy herbicides-2,4-D), and to prevent nephrotoxicity from the renal deposition of myoglobin after severe rhabdomyoiysis or precipitation of methotrexate. (While enhanced elimination may be achieved, it is uncertain if clinical outcomes are improved with this therapy.) Also recommended by REAC/TS for internal contamination of uranium from radiation emergencies to prevent acute tubular necrosis (see Radiation, p 327). 

The falling pH value and the high temperature cause protein denaturation. Soluble proteins precipitate and scatter light. Consequently, the meat appears paler in spite of the unchanged myoglobin content. At the same time, cell membranes disintegrate and water loss increases. In fact, PSE pork incurs up to 15% drip loss in 3 days and normal meat only ca. 4%. 

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