Denaturation

What happens when a raw egg hits a hot pan?

The clear, gooey egg whites turn opaque and solid. Heat causes proteins in the egg to undergo denaturation: the proteins unfold and lose their three-dimensional structure.

Think of a protein like a sticky string. A folded protein has all the sticky bits stuck to one another, keeping the string coiled up in a specific shape. Heat makes molecules move and jiggle - the more heat, the faster molecules move. At high enough temperatures, the jiggling uncoils the protein, turning it into a loose, floppy string. The exposed sticky bits can now get attached to other protein molecules. This is why the egg white turns solid: the denatured proteins stick to one another, forming a solid aggregate.

Besides heat, other factors can cause protein denaturation by interfering with the amino acid interactions that stabilize the folded structure (in other words, changing the "stickiness" of different parts of the protein string). Changes in pH can disrupt hydrogen bonding. Salt ions can prevent salt bridges from forming between amino acid side chains. Reducing agents can break disulfide bonds.

Denaturation

Denaturation is a process of disruption which results in a change in a protein's structure, which in turn affects its function. This occurs when the bonding interactions are disrupted.

Some possible causes of denaturation include heat, alcohol, and heavy metal salts.

Reference:

Elmhurst College

Temperature typically affects the tertiary structure and pH change typically affects the secondary structure. Both changes (pH and temperature) are forms of denaturation. We know that acidity affects Hydrogen levels so it is logical that the secondary structure which is made up from H-bonds, is affected during this form of denaturation. For temperature denaturation the R-groups are changed so tertiary Structure is affected.