Protein precipitation proteins

White wines contain relatively large amounts of insoluble proteins that slowly precipitate from the solution (the initial protein precipitation begins during pressing). Most white wines are to deficient in phenolics, causing a quick and complete protein precipitation. Protein haze may be due to the fraction of residual wine proteins that have been rendered prone to precipitation by their interaction with reactive phenolics (from the grape, and also rarely from the cork). Bentonite removes different amounts of grape protein fractions (Moine-Ledoux and Dubourdieu 1999). 

Protein precipitation Protein removal for plasma sample analysis Decreases protein solubility using chaotropic agents Commonly available equipment and reagents... 

Brucke s reagent (protein precipitant) dissolve 50 g of K1 in 500 mL of water, saturate with Hglj (about 120 g), and dilute to 1 liter. 

The protein precipitate is washed with water, redispersed at pH 7, and then spray dried. Typical commercial soy protein isolates contain greater than 90% cmde protein, dry wt basis. 

Factor VIII, immunoglobulin, and albumin are all held as protein precipitates, the first as cryoprecipitate and the others as the Cohn fractions FI + II + III (or FII + III) and FIV + V (or FV), respectively (Table 7, Fig. 2). Similarly, Fractions FIVj + FIV can provide an intermediate product for the preparation of antithrombin III and a-1-proteinase inhibitor. This abiUty to reduce plasma to a number of compact, stable, intermediate products, together with the bacteriacidal properties of cold-ethanol, are the principal reasons these methods are stiU used industrially. 

Silver nitrate is astringent and a protein precipitant, which is not medically desirable. Other forms of silver have been used to avoid this problem, including coUoidal silver, silver-protein preparations, and finely divided silver metal called Katadyn silver. 

S ts can be used to precipitate proteins by salting out effects. The effectiveness of various salts is determined by the Hofmeister series, with anions being effective in the order citrate > PO4" > SO4" > CH3COO > Cl > NO3 , and cations according to NH4 > > Na ... 

Water-soluble polymers and polyelectrolytes (e.g., polyethylene glycol, polyethylene imine polyacrylic acid) have been used success-hilly in protein precipitations, and there has been some success in affinity precipitations wherein appropriate ligands attached to polymers can couple with the target proteins to enhance their aggregation. Protein precipitation can also be achieved using pH adjustment, since proteins generally exhibit their lowest solubility at their isoelectric point. Temperature variations at constant salt concentration allow for frac tional precipitation of proteins. 

The preliminary precipitation of proteins from milk is realized through the addition of solutions of acetic acid (1,7 mol/1) and sodium acetate (lmol/1) at t = 40-45°C before chromatographic isolation of OxTC. The precipitated proteins are separated by filtration. OxTC is detenuined in filtrate after its isolation on chromatographic column. Contents of OxTC was determined on calibration curve which is linear within concentration range 0,01-1,0 p.g/ml. 

Crystallization of proteins can be difficult to achieve and usually requires many different experiments varying a number of parameters, such as pH, temperature, protein concentration, and the nature of solvent and precipitant. Protein crystals contain large channels and holes filled with solvents, which can be used for diffusion of heavy metals into the crystals. The addition of heavy metals is necessary for the phase determination of the diffracted beams. 

For precipitated protein, buffered solutions containing chaotropic reagents such as 0.1% SDS, 8 M urea, or 6 M guanidine or proteolytic enzymes such as pepsin may be used. However, an extended washing with buffer is required to remove SDS and guanidine. Unexpected elution behavior can occur if these reagents are not removed completely. 

Purification of photoprotein. The dialyzed photoprotein solution was centrifuged to remove precipitates, and then subjected to fractional precipitation by ammonium sulfate, taking a fraction precipitated between 30% and 50% saturation. The protein precipitate was dissolved in 50 ml of 10 mM sodium phosphate, pH 6.0, containing 0.1 mM oxine ( pH 6.0 buffer ), dialyzed against the same buffer, and the dialyzed solution was adsorbed on a column of DEAE-cellulose (2.5 x 13 cm) prepared with the pH 6.0 buffer. The elution was done by a stepwise increase of NaCl concentration. The photoprotein was eluted at 0.2-0.25 M NaCl and a cloudy substance (cofactor 1) was eluted at about 0.5 M NaCl. The photoprotein fraction was further purified on a column of Sephadex G-200 or Ultrogel AcA 34 (1.6 x 80 cm) using the pH 6.0 buffer that contained 0.5 M NaCl. 

In addition it should be added that microdisperse forms of CP can precipitate proteins from solutions. Figs. 21-23 show that CP microdispersions with particle size of 1-2 pm precipitate serum albumin from solutions [81] in complete agreement with general flocculation laws for polyelectrolytes. The figs, show an extreme... 

From animal tissue, especially bovine lung and liver (e. g. autolysis of comminuted tissue parts, heating with ammonium sulfate in alkaline solution, filtration and acidification yield heparin as complex with protein, removal of fat with alcohol and treatment with trypsine for the purpose of decomposition of proteins, precipitation with alcohol and various purification methods). 

Fig. 1. Relationship between reactor mean velocity gradient and particle size for isoelectric soya protein precipitate. Open symbols represent precipitate diameter for 50% oversize Closed symbols represent precipitate diameter for 90% oversize [51]...

Fig. 2. Flow of protein precipitates through various pumps [107]...

Protein precipitate, insect cells Hvbridoma. Mammalian cells... 

Protein precipitate, hybridoma cells Insect cells Mammalian Cells... 

A similar approach has been suggested in other studies of plant cells [57] and protein precipitates [133]. However, information on the rate of the size distribution shift process cannot be inferred from chain-length measurements made only at the beginning and end of the experiment. To date, there have been no reports on the progressive modification of the size distribution of plant cells subjected to continued exposure to turbulent forces. There are, however, a number of studies which address the break-up of mycelial hyphae in agitated vessels... 

Many use the hexokinase procedure without protein precipitation. That this is a procedure which is not acceptable is illustrated in Table II where it is shown that unless hemoglobin is removed there will be interference in the results obtained. In severely hemolyzed blood, errors as high as 25% are not uncommon. 

If the fluorometric procedure is used, with protein precipitation, then bilirubin will not interfere with the hexokinase procedure. Even if protein precipitation is not resorted to, the interference from bilirubin does not become significant until one is dealing with an infant in severe jaundice. This can be seen in Table III. 

If the fluorometric method is used after protein precipitation then the glucose can be readily assayed on 1 pi of plasma with the hexokinase procedure. 

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