Salt fractionation

Coiicin E (from E.coli) [11032-88-5], Purified by salt extraction of extracellular-bound colicin followed by salt fractionation and ion-exchange chromatography on a DEAE-Sephadex column, and then by CM-Sephadex column chromatography [Schwartz and Helinski J Biol Chem 246 6318 1971],... 

Salt fractionation (eg, precipitation of proteins with ammonium suifate)... 

Elution in salts fraction during DEAE-cellulose chromatography... 

Heide, K. and Schwick, H. G. (1978) Salt fractionation of immunoglobulins, in Handbook of Experimental Immunology (Weir, D. M., ed.), Blackwell Scientific Publications, Oxford. 

L9. Levin, B., and Oberholzer, V. G., Paper electrophoresis of serum proteins with micro Kjeldahl nitrogen analysis of the protein fractions A comparison with free electrophoresis and salt fractionation methods. Am. J. Clin. Pathol. 23, 205 (1953). 

The presence of D-fructose does not interfere with the isolation of aldo-benzimidazoles by the above method. It has no effect on the potassium salt fraction but it will precipitate with the barium salts, and later, by degradation, may give rise to small amounts of D-arabo-ben-zimidazole. Therefore, say Moore and Link,16 in the examination of natural products the isolation of D-arabo-benzimidazole from the barium salt fraction, rather than from the potassium salt fraction as expected, is to be regarded with suspicion, for it may have been formed from D-fructose instead of D-arabinose. They suggest in questionable cases that pentose and ketose tests then be tried on the original sample as an aid in solving the problem. 

Since these earlier studies a variety of different methods and techniques have appeared for purifications of the serum transferrins. Precipitation of human serum transferrin by rivanol appears to have been used widely as an initial purification step (17, 18, 80, 107). A method for the preparation of large quantities of human serum transferrin was proposed by Inman et al. (69). The Inman method employed solvent and salt fractionation and cellulose ion exchange chromatography. A number of other workers have used cellulose ion exchange chromatography in combination with other procedures, such as electrophoresis (14, 22, 57, 105, 112, 137). 

Scaffold sample Theoretical scaffold porosity (%) Salt fraction Salt grain sizes based on sieving ( im)... 

Figure 4. Comparison between scaffolds porosity obtained via different measurement techniques for samples A to E containing different salt fractions.

The transfer of labeled amino acids from aminoacyl sRNA to purified rat-liver ribonucleoprotein particles has been shown to require GTP, and a soluble portion (pH 5 Supernatant) of the cell. An enzyme fraction, aminoacyl transferase (or polymerase) I, purified from the pH 5 Supernatant was found to catalyze the transfer of amino acid to protein with microsomes, but not with the more purified ribonucleoprotein particles (ribosomes). When transferase I was supplemented with glutathione and a microsomal extract, microsomal aminoacyl transferase (or polymerase) H, transferring activity was restored. Since the pH 5 Supernatant was active in catalyzing the transfer of amino acids from sRNA to ribosomal protein, it was concluded that both transferring activities were present in this crude fraction. Resolution of the two activities from the pH 5 Supernatant fraction was obtained by salt-fractionation procedures. Neither enzyme fraction was active when incubated individually or with glutathione, but together in the presence of... 

Our third approximation is a brutal one, but it is consistent with the prediction that the minimum in the pair potential always lies at 4/k and should give reasonable results in the limit of dilute electrolyte solutions. With this simplification, we can obtain a clean analytical prediction for the salt-fractionation effect. 

This in turn gives the ratio of these two quantities, the salt-fractionation factor s, as... 

The values for g obtained from Equation 4.22 do not seem to be very different from those obtained from Equation 4.20, as shown in Table 4.1 and Figure 4.3a. It is easy to see that g must be equal to /2 as Os tends to zero by expanding the exponentials in the linear approximation (Debye limit). Naturally, Equation 4.15 gives us i = 1 in this limit, as an uncharged layer does not expel co-ions and salt is equally distributed between regions I and II. However, as shown in Table 4.2 and Figure 4.3b, the predicted salt-fractionation effect obtained by substituting Equation 4.22 into Equation 4.15 is markedly different from the Donnan equilibrium. 

For low surface potentials ( s < 1), the salt-fractionation factors calculated (a) via the coulombic attraction theory and the electric integral solved by Equation 4.20 (i.e., via the Donnan equilibrium) and (b) via the coulombic attraction theory and the electric... 

Some Illustrative Values of the Salt-Fractionation Factor (s) as a Function of the Surface Potential (y/0)... 

Twelve Sets of Results Obtained for the Salt Fractionation Effect... 

Note r is the sol concentration, c is the salt concentration of the solution added to the crystals, W is the number of washes that the crystals were given and Ns is the number of samples used under each set of conditions. Measured salt concentrations in the supernatant fluid cex and the gel phase cgd and the salt fractionation factor s=cex/cgel, are given in the form a <7, where a is the average result and exits standard deviation. The exception is the r = 0.01, c = 0.03 M result, for which only the average values are given. 

FIGURE 5.5 The salt fractionation effect in n-butylammonium vermiculite swelling. The salt fractionation factor s = ceJc x is plotted as a function of cex, the salt concentration in the supernatant fluid. The solid line shows the coulombic attraction theory prediction, s = 2.8. 

---