An Explanation of the Process of Hydrolysis
In its simplest definition, hydrolysis is a chemical reaction in which water is used to break down the bonds of a particular substance. In biotechnology and as far as living organisms are concerned, these substances are often polymers (simply put, many similar molecules can that join together).
The word hydrolysis comes from the word hydro, which is Greek for water, and lysis, which means "to unbind." In practical terms, hydrolysis means the act of separating chemicals when water is added. There are three main types of hydrolysis: salt, acid, and base hydrolysis.
Hydrolysis can also be thought of as the exact opposite reaction to condensation, which is the process whereby two molecules combine to form one larger molecule. The end result of this reaction is that the larger molecule ejects a water molecule.
3 Common Types of Hydrolysis
- Salts: Hydrolysis occurs when salt from a weak base or acid dissolves in liquid. When this occurs, water spontaneously ionizes into hydroxide anions and hydronium cations. This is the most common type of hydrolysis.
- Acid: Water can act as an acid or a base, according to the Bronsted-Lowry acid theory. In this case, the water molecule would give away a proton. Perhaps the oldest commercially-practiced example of this type of hydrolysis is saponification, the formation of soap.
- Base: This reaction is very similar to the hydrolysis for base dissociation. Again, on a practical note, a base that often dissociates in water is ammonia.
What Is a Hydrolysis Reaction?
In a hydrolysis reaction involving an ester link, such as that found between two amino acids in a protein, the molecule is split. The resulting product is a split of the water molecule (H2O) into an OH and an H+ that form a hydroxyl (OH) group, and another that becomes a carboxylic acid with the addition of the remaining hydrogen proton (H+).
Reactions in Living Organisms
Hydrolysis reactions in living organisms are performed with the help of catalysis by a class of enzymes known as hydrolases. The biochemical reactions that break down polymers, such as proteins (which are peptide bonds between amino acids), nucleotides, complex sugars or starch, and fats are catalyzed by this class of enzymes. Within this class are lipases, amylases, proteinases, hydrolyzed fats, sugars, and proteins, respectively.
Cellulose-degrading bacteria and fungi play a special role in paper production and other everyday biotechnology applications because they have enzymes (such as cellulases and esterases) that can break cellulose into polysaccharides (ii.e., polymers of sugar molecules) or glucose, and break down stickies.
For example, proteinase could be added to a cell extract, to hydrolyze the peptides and produce a mixture of free amino acids.