Protein Denaturation

Certain situations or conditions can denature proteins, such as extreme temperature, pH, or salt concentrations. Also, chemical or reducing agents can denature proteins as well. A typical example of a reducing agent is beta-mercaptoethanol, which denatures proteins through the disruption of disulfide bonds. Disulfide bonds form between cysteine residues and are formed by oxidation reactions. So, in order to break disulfide bonds, the opposite of oxidation (reduction) is necessary.

An example of a chemical agent that can denature proteins is urea. Urea contains many groups capable of forming hydrogen bonds. It will disrupt hydrogen bonds on proteins and prevent proteins from forming hydrogen bonds with themselves. In this way, proteins will form hydrogen bonds with urea and unfold. Also, sodium dodecyl sulfate (SDS) is a detergent that can denature proteins as well. As a detergent, SDS breaks down and disrupts many interactions in proteins and causes them to unfold. SDS is useful in laboratory techniques like gel electrophoresis (specifically SDS-PAGE) because in denaturing proteins, it gives them an overall negative charge, thus allowing the experimenter to eliminate the effect of charge during electrophoresis and therefore separate proteins based on size alone.

It is important to note that although all of these methods can denature a protein, sometimes it is more effective to use more than one at the same time. For example, in some gel electrophoresis experiments, both SDS and the reducing agent beta-mercaptoethanol are utilized simultaneously, leading to more effective protein denaturation.