Protein: gluten formation

Wheat and other related grains (including barley and rye) contain a mixture of two proteins glutenin and gliadin.  When flour made from grinding these grains is mixed with water the two proteins combine to form gluten. Without water, gluten is not formed.

Protein: coagulation

Coagulation is defined as the change in the structure of protein (from a liquid form to solid or a thicker liquid) brought about by heat, mechanical action or acids.  Enzymes may also cause protein coagulation e.g. cheese making.