fractions, respectively. It shows two major fractions: 2S albumins and 11S globulins (also named helianthinin). Helianthinin, a globular oligomeric p
R
t with a
molecular weight of 300–350 kDa and this p
R
t mainly exists in the 11S hexametric
form.
23.4 Isolation of p
R
t
They can use selective precipitation of p
R
t as: Fractionate a subset of p
R
t from a p
R
t
solution. Bulk method used major recovery of the p
R
t from a crude lysate and
recover a single p
R
t of interest from a purification step.
23.4.1 Selective Precipitation Methods
23.4.1.1 Salting Out
They apply ammonium sulfate to form co precipitation with p
R
t because the saturation concentration provides high molarity. It causes precipitation of most p
R
t , and
does not have a large heat of solution. So, the generated heat gets easily dissipated;
a saturated solution (4.40 M at 20 °C) of p
R
t has a density of 1.235 g/cm
3 , does not
interfere with the precipitated p
R
t sedimentation by centrifugation. It also has
bacteriostatic properties and its concentrated solutions are protecting most p
R
t from
denaturation in solution state.
23.4.2 Isoionic Precipitation
23.4.2.1 Column Method
p
R
t are less soluble and showing more precipitation when they are isoionic. The p
R
t
are their least hydrated conformation (a phenomenon that closely associated to the
condition of p
R
t at their isoelectric point) when they are isoionic salt- free state. Tan
ford proposes the procedure applicable for this method. To determine the solubility
of many p
R
t , it applies two important parameters:( a) Low salt concentration (0 to
0.1 to 0.2 M salt) (b) Solution pH regarding each p
R
t Isoionic point. Column
method can determine by adjusting the p
R
t to their Isoionic pH to p
R
t that remain
soluble at their Isoionic point to strip away all salts from p
R
t the mixed-bed
deionization methods.
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