Gluten

Gluten proteins form long chains that stick to each other.

Gluten is an interconnected network of coiled chains made up of gliadins and glutenin proteins. Each of these proteins is around 1000 amino acids long. Gliadin chains fold onto themselves in a compact mass.  These proteins act as ball bearings for glutenin proteins. Glutenins have sulfur-containing amino acids at the end of their chains. Where gliadins only form weak bonds, glutenins form strong sulfur-sulfur bonds with each other, forming long chains. Amino acids in the glutenin chains also form weak temporary hydrophobic bonds that form the coil. The coiled and kinky gluten molecules makes the dough elastic. Thus when dough gets stretched out, the coils extend. When the tension is released, the kinks and coils reform, and the dough shrinks back to its original shape. These properties of plasticity and elasticity allow wheat dough to accomodate carbon dioxide gas without allowing it to escape.