Purification of Alkaline Protease from Chicken Intestine by Aqueous Two Phase System Of Polyethylene Glycol and Sodium Citrate

An aqueous two phase system of polyethylene
glycol (PEG) and salts was evaluated for separation and
purification of alkaline proteases from chicken intestine.
Among the different salts evaluated potassium phosphate
and sodium citrate gave higher enzyme yield (73.5% and
69.7% respectively) and enzyme purification (5.3 and 7.4
fold) in PEG rich upper phase. Increase in concentration of
sodium citrate in the system resulted in reduction in enzyme
yield and enzyme purification factor, with 15% salt
showing highest enzyme yield (59.8%) and purification
(6.7 fold). Initial protein concentration in the system did not
show any specific trend on the partition behavior of the
enzyme. The temperature at which the system is incubated
did not show any significant (p≥0.05) effect on enzyme
partition and purification. Increasing the PEG concentration
in the system from 15 to 25% resulted in reduction in
enzyme yield from 53.7 to 21.9% and enzyme purification
from 5 fold to 1.4 fold in PEG rich upper phase. pH also
had a significant (p<0.05) effect on the partition of the
enzyme to the upper phase with highest purification (3.4
fold) at pH 9.0 and higher enzyme yield (46.2%) at pH 10.