3.6: Hydrolysis

Overview

Hydrolysis is a chemical reaction in which the addition of water breaks down a polymer into its simpler monomer units. For example, peptides break into amino acids, carbohydrates into simple sugars, and DNA into nucleotides. Enzymes often facilitate these processes.

Hydrolysis Reverses Dehydration Synthesis

Complex carbohydrates can be broken down by breaking the bonds between individual sugar units. The reaction breaks a glycosidic bond as water is added to the compound. The glycosidic bonds between sugar molecules are unstable and are susceptible to hydrolysis. Hydrolases are a class of enzymes that often catalyze hydrolysis.

Different types of glycosidic bonds (e.g., 1-4 linkage, 1-6 linkage) require different hydrolases. For instance, starch primarily consists of α-1-4 linked glucose, with a relatively small number of α-1-6 glycosidic bonds. While α-amylase can cleave α-1-4 glycosidic bonds in the middle of the polymer, the enzyme amyloglucosidase breaks only terminal α-1-6 or α-1-4 bonds (i.e., the last glucose units at the ends of the chain).

The Lack of Lactase Can Cause Gastrointestinal Symptoms

Human babies produce the enzyme lactase, which catalyzes the hydrolysis of milk sugar (lactose) - a disaccharide made up of glucose and galactose. As people age, the production of lactase decreases, leading to lactose intolerance. In some cases, the body may fail to produce lactase due to a genetic disorder. In the absence of lactase, lactose directly passes into the colon through the intestine without breaking down into its monomers. Colonic bacteria can metabolize lactose and release gas as a byproduct, resulting in water influx, bloating flatulence, and even diarrhea. These symptoms can be mitigated by either taking lactase supplements or removing dairy from the diet altogether.

Hydrolysis reactions, which are the addition of water to a molecule, are one way a polymer breaks down into its constituent molecules.

It is the opposite reaction of dehydration synthesis, which creates large molecules from smaller monomers through the loss of water.

During an enzyme-assisted hydrolysis, water molecules are consumed. A hydroxyl group binds to one monomer, and a hydrogen atom to the other, leading to the breaking of the bond between two monomer units.

For example, the unbranched polysaccharide amylose is composed of repeating monomers of ɑ-glucose. 

The enzyme amylase uses water to hydrolyze amylose into the disaccharide maltose, which is then further hydrolyzed by the enzyme maltase into glucose subunits. 

The newly released monomers can be repurposed into different polymers via dehydration synthesis depending on the requirements of the cell.

Hydrolysis – A chemical reaction where water is added to break polymers into their monomer components. Dehydration synthesis – A reaction that forms bonds between monomers by removing a water molecule. Glycosidic bond – A covalent bond between sugars that is cleaved during carbohydrate hydrolysis by enzymes. Hydrolase – An enzyme that uses water to catalyze the cleavage of chemical bonds in biological molecules. Lactase – An enzyme that breaks lactose into glucose and galactose, aiding digestion in the small intestine.

Define Hydrolysis – Describe how it breaks polymers into monomers by adding water (e.g., starch to glucose) Contrast with Dehydration Synthesis – Explain the reverse process that builds polymers by removing water (e.g., forming proteins). Explore Enzymatic Specificity – Understand how enzymes like amylase break glycosidic bonds (e.g., starch digestion). Explain Enzyme Deficiencies – See how lack of enzymes like lactase leads to intolerance Apply to Biomolecule Breakdown – Relate hydrolysis to digestion of proteins, sugars, nucleic acids

Questions that this Hydrolysis video will help you answer: What is hydrolysis and how is it used in biology? What does hydrolysis do in breaking down molecules? What is a hydrolysis reaction in biochemical processes?

This Hydrolysis video is useful for: Students – Understand how biological macromolecules like proteins and sugars are broken down through hydrolysis. Educators – Provides a clear framework to explain enzyme function and digestion in biochemistry lessons. Researchers – Connect hydrolysis and enzyme specificity to metabolic and digestive pathways. Science Enthusiasts – Offers insights into the chemistry behind food digestion at the molecular level. .