Separation of biomolecules by precipitation from aqueous broth
is the most traditional method for the recovery and partial purification
of enzymes. It is an easy technique with simple equipment
requirements, low energy needs, easy scale-up and the possibility
of using a large number of precipitants, including some inexpensive
ones, such as ethanol, which is widely produced in Brazil and worldwide
[4]. Organic solvents that do not denature biological products,
like enzymes, can also be used, and the precipitate formed is often
more stable than the soluble material. Interactions between the
solvent and internal hydrophobic areas may cause an irreversible
denaturation of the enzyme that disrupts the normal secondary
forms (a-helix and b-sheets), and uncoils it into a random shape
[6]. This can be minimized by reducing the temperature to values
around zero or below, because at low temperature the flexibility of
the biomolecule is less, reducing the penetration capability of the
solvent and any irreversible denaturation of enzymes, minimizing
the loss of activity [4]. Ethanol precipitation is a promising technique
that can be applied to the purification of different enzymes [6–9].