Protein precipitation precipitate behavior

The introduced THEOS did not bring about precipitation in protein solutions. This behavior differs from that observed with common silica precursors. For example, TEOS added in such small amounts caused precipitation. By using THEOS, we could prepare homogeneous mixtures. When its amount introduced into the albumin solution was less than 5 wt.%, there was no transition to a gel state (Table 3.1). A gradual increase in THEOS concentration resulted in a rise in the solution viscosity. The transition to a gel state took place as soon as a critical concentration was reached. Its value, as demonstrated in Ref. 

Spider silk proteins from plants remain soluble at high temperatures, allowing them to be enriched by boiling [26]. In order to enrich the spider silk-ELP fusion protein, we therefore exposed tobacco leaf extracts to heat treatment at 95°C for 60 min and then cleared the supernatant by centrifugation. In further steps, the reversible precipitation behavior of ELP fusion proteins was exploited to develop a suitable purification strategy. For the selective precipitation of SOl-lOOxELP, NaCl was added at a final concentration of 2 M and the temperature was increased to 60 °C. In this man-... 

While the Hofmeister series and the Cohn-Edsall and Setschenow equations are useful tools for the estimation of protein stability and precipitation behavior, their usefulness is limited because of the lack of a quantitative relationship to molecular or solution properties. The goal of past and current efforts is to quantify the Hofmeister series and to predict the constants Ks and /3 (or Ks and log [E]0) in the Cohn-Edsall or Setschenow equations, respectively. Some of the most relevant efforts focus on ... 

Proteins are both colloids and polymers. Therefore, attempts have been made to understand the phenomenon of protein aggregation with the help of models from the polymer and colloid fields such as DLVO theory, describing the stability of colloidal particles, or phase behavior and attraction-repulsion models from polymers (De Young, 1993). For faster progress, more phase diagrams for equilibrium protein precipitation, in both the crystalline and the non-crystalline state, as well as more data on observations of defined protein oligomers or polymers, are required. 

Rates of crystal nucleation and growth generally have different dependencies on protein supersaturation, and additionally vary substantially for different protein—precipitant systems. This can lead to a variety of unexpected behaviors in crystallization experiments. The nucleation... 

In order to distinguish between nonpro-tein-bound platinum and unbound cis-Pt or carbo-Pt, trichloroacetic acid (TCA) protein precipitation, or the precipitation of plasma proteins with cold ethanol and ultrafiltration, can be used (Ma et al. 1996). Other batch-type experiments were reported to study the binding behavior of Pt-compounds using ET-AAS as the determination method (Parsons et al. 2003). Gel-permeation chromatography was used to study Pt species in extracts from plants treated with Pt-salts (Messerschmidt et al. 1994), while Alt et al. (2002) studied the bonding stage of Pd in endive. 

Precipitation of protein for turbidimetric or nephelometric assays, which can be achieved with sulfosalicylic acid alone, sulfosalicylic acid with sodium sulfate or trichloroacetic acid, or trichloroacetic acid alone. Precipitation methods for total protein assay require that both globulins and albumin are efficiently precipitated with the formation of small, well-dispersed particles of consistent size so that light scattering is a reproducible phenomenon. The particles must be homogeneously suspended in the medium at all times. Standard material must have as nearly as possible the precipitation behavior of normal and abnormal mixtures of plasma and proteins. Specific turbidimetric precipitation methods have been described for total protein determination in urine and CSF. 

An LC-MS-MS method to study the pharmacokinetic behavior of adefovir, an antihepatitis B virus drug. Following protein precipitation the sample is analyzed on a C18 column, using a triple-quadrupole tandem mass spectrometer as detector in the positive electrospray ionization mode and PMPA as the internal standard. The method is hnear in the concentration range 0.25-100 ng/ml, with the lower hmit of quantification 0.25 ng/ml. The intra- and interday relative standard deviation over the entire concentration range is <5.7%. The accuracy determined at three concentrations is within 2.5% relative error. The method was successfully used in pharmacokinetic studies. 

Butyl alcohols solubilize the ocytocic substances only from extracts treated with acids at a pH close to 3.9, at which pH proteins precipitate. The same phenomenon is true of hog pituitary. This behavior is due to the ocytocin-protein-complex which may represent the mother molecule of Van Dyke. 

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. 

It did not give rise to phase separation or precipitation. Similar behavior was observed when other types of polysaccharides were examined [53,54]. By now all the commercially important polysaccharides have been applied to the fabrication of hybrid silica nanocomposites in accordance with Scheme 3.2. What is more, various proteins have been entrapped in silica by the same means. In all instances the THEOS demonstrated good biocompatibility with biopolymers, even though its amount in formulations was sometimes up to 60 wt%. Biopolymer solutions after the precursor admixing remained homogeneous to the point of transition into a gel state. 

There is much indirect evidence that the above hypothetical mechanism fits the behavior of the soy proteins. Wolf and Tamura (2), while studying the heat denaturation of native IIS soy protein, found that soluble aggregates are formed prior to the formation of insoluble precipitates. They proposed the following mechanism to explain their results. 

Figure 3-4 Hypothetical behavior of a solution containing three proteins, A, B, and C, upon ammonium sulfate fractionation. The concentration of protein remaining in the solution is plotted against ammonium sulfate concentration (usually expressed as % saturation). Addition of ammonium sulfate to concentration c, will precipitate largely protein B, which can he removed by centrifugation. Addition of additional salt to c2 will precipitate largely protein C, while A remains in solution.

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