3.6:
Hydrolysis
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.
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.