Protein concentration changes

Although the spectrophotometric assay of proteins is fast, relatively sensitive, and requires only a small sample size, it is still only an estimate of protein concentration. It has certain advantages over the colorimetric assays in that most buffers and ammonium sulfate do not interfere and the procedure is nondestructive to protein samples. The spectrophotometric assay is particularly suited to the rapid measurement of protein elution from a chromatography column, where only protein concentration changes are required. 

Bilirubin concentrations and serum enzyme elevations give a static picture of the liver s condition and are not good indicators of hepatic function. Clinically available tests to predict hepatic function include measurement of serum proteins (albumin or transferrin). As a hepatic function decreases, serum protein concentrations in the body decrease at a rate determined by each protein s own elimination rate. Overhydration and starvation can also decrease serum protein concentrations. Changes in the prothrombin time often occur earlier than the changes in albumin or transferrin. The response of the prothrombin... 

Determining protein concentration changes as a function of reactor operating time will yield more accurate information about system performance changes. See Figure 4.3 as an example of how to plot pg-protein" cm" and pmol e" pg-protein" cm". ... 

There is much evidence to suggest that the metastable liquid-liquid region of a protein solution is responsible for cataract formation. As the eye ages, its protein concentration changes and one (or more) proteins may achieve a concentration that exceeds the saturation concentration as indicated in the figiue. Following phase separation, the highly concentrated liquid phase does not set-tie but remains in the eye as a fine dispersion whose optical properties seriously interfere with vision. The experimental data show that when the concentration of native y-crystaUin exceeds about 100 mg cm at body temperature (310 K, 37 °C), a second liquid phase is formed whose concentration is about 700 mg cm. It is this... 

Fig. 31. Effect of pressure on flux in stirred batch-ceU ultrafilttation experiments. As the protein concentration in the feed solution increases, the maximum achievable flux decreases. The maximum flux can be adjusted by changing the turbulence in the cell (71). A, 0.9% saline B, 0.65% protein (1830 tpm) C, 3.9% protein (1830 rpm) D, 6.5% protein (1830 rpm) and E, 6.5% protein (880 rpm). To convert kPa to psi, multiply by 0.145.

All proteins, independent on their aminoadd con odtion, aher the refi active index of water by a dmilar amount per unit mass, and thus there is a linear correlation between the surfiice concentration of protein and the resonance angle shift. 1000 resonance units (RU) corre ond to a 0.1° shift in the SPR angle and this is equivalent to a surfiice concentration change of about 1 ng mmr. ... 

In Chapter 1 (Section 1.2.4.3), the Hill equation and the Hill coefficient, nH, are described. Hill coefficients greater than or less than unity are often interpreted as indicating positive or negative cooperativity, respectively, in the relationship between receptor occupancy and response. For example, positive cooperativity could arise due to amplification in a transduction mechanism mediated by G-proteins and changes in cell calcium concentration. 

Weller R F and Cooper A (2001), Seasonal changes in crude protein concentration of... 

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