Gluten and Its Biochemistry
What is a Protein?
A protein is a large chemical structure in all living organisms. Proteins have many uses, ranging from the development and repair of tissues, enzymes, and hormones, to acting as the building blocks for bones, muscles, and more. Proteins are made up of smaller structures known as amino acids. Each protein is unique in that it has a different order or variation of amino acids like A-A-A-B or C-C-A-B, where those letters are symbolic for an amino acid sequence. This sequence of amino acids gives each protein its identity, special properties, and functionality.
What is the Chemical Composition of Gluten?
Gluten is a protein known as a storage protein, which is a specific type of protein that serves as a storing reserve for amino acids and other components that are used by the body.
Proteins are often composed of different components, sometimes even other proteins. Within gluten, there’s another storage protein known as prolamin. The storage protein prolamin contains a very high amount of a specific amino acid known as proline. Remember, amino acids are the building blocks of proteins. So the storage protein, prolamin, is made up of a lot of proline. The specific prolamins that make up gluten are gliadin (from wheat), hordein (from barley), and secalin (from rye). Now, prolamins can be broken down even further into 2 sub categories: gliadins and glutenins, which are 2 other types of proteins. Gliadins are water soluble, whereas glutenins are not water soluble. It is important to note that although the prolamins in each grain type are named differently, each type does contain gliadin.
Overall, gluten is composed of many proteins. One of those proteins is prolamin, which is also composed of 2 proteins, gliadin and glutenin. Gliadin is responsible for the thickening and viscous texture of gluten. Whereas glutenin is responsible for the elasticity and toughness of gluten.
How Does Gluten Chemically Affect Food?
Gluten is not water soluble, meaning that it cannot dissolve by putting it in water. It comes from a latin word which means “glue.” Why is it important that gluten is insoluble in water? In water containing dough mixtures, the gluten does not dissolve, but it binds together through specific types of chemical bonding. When this occurs, gluten is binding to other gluten structures, in order to create a certain structure or shape. This shaping allows for starch molecules and carbon dioxide molecules to be trapped within the gluten clusters. Due to the starch and carbon dioxide being trapped in the middle of these structures, it gives bread a light and fluffy texture.
How Does Gluten Affect People During Digestion?
To recap, gluten is a protein that is made of amino acids. Whenever you have a sequence of 2 or more amino acids, it is called a peptide. When proteins are digested (or degraded) in the body, enzymes in the body cleave off long chains of peptides (amino acid chains). Once these peptides are digested, they are absorbed through the intestines and then transported and used by the body. Especially for Celiac Disease, there are 3 peptide sequences that have been known to initiate an immune response. There is 1 gliadin peptide sequence in particular that initiates a very aggressive immune response. This peptide contains 33 amino acids in its chain and is known to be the main cause of immune response in individuals with Celiac Disease. These immune responses can cause many different effects, most notably inflammation which can lead to many other secondary issues.
Conclusion
In conclusion, gluten is made of many proteins, notably prolamin. Prolamin also has proteins that comprise it, most notably gliadin and glutenin. Both have effects on giving bread it’s common texture that we have all come to know and desire. Gliadin, specifically a 33 amino acid sequence of it, is responsible for the symptoms and effects that individuals with Celiac Disease experience when exposed to gluten. The only way to completely alleviate the effects of gluten is to create a 100% gluten-free life, eliminating all exposure to gliadin.