CHAPTER 19: Unit 8. Amino Acids and Proteins Denaturation

Denaturation of protein

There are five factors affecting the protein structure. These five factors can affect the biological benefits of the protein.

The extreme conditions such heat, changing the pH of medium, reaction with organic compounds, addition of metal ions and agitations can destroy and denature the protein and cause the protein to be biologically inactive.

Denature can cause both secondary and tertiary protein structure. The primary protein structure will remain unaffected since the peptide interaction is strong and cannot be decomposed by such factors unless very extreme conditions are used.

These factors are:

1. Heat
2. Acids and Bases
3. Organic Compounds
4. Heavy Metal Ions
5. Agitation

The figure below illustrates these denaturation effects:

Reference: http://chemistry.elmhurst.edu/vchembook/568denaturation.html

1.  Heat:Heat can destroy the hydrogen bond and the hydrophobic interactions between none polar R groups. The value of food nutrition is not changed.

2. Acids and Bases:A change of pH will affect the hydrogen bonds and destroy the salt bridge.

3. Organic Compounds:Organic compounds such as alcohol can destroy hydrogen bonds and destroy the side chain intra molecular hydrogen bonding.

4. Heavy Metal Ions:Heavy metal ions can denature the protein by forming bonds with ionic R groups. Also, heavy metal ions can react with the S-S bridges. The protein that has heavy metal ions is considered to be poisonous.

5. Agitation:Mechanical agitation can denature the protein. It does stretch the polypeptide chains and hence destabilizes the interactions between the chains.