Proteolysis

Proteolysis is the directed degradation (digestion) of proteins by cellular enzymes called proteases or by intramolecular digestion.

Purposes

Proteolysis is used by the cell for several purposes. They include:

• Removal of N-terminal methionine residues after translation.
• Removal of the signal sequence of peptides after their transport through a membrane
• Separation of viral proteins that were translated from a polycistronic mRNA
• Digestion of proteins from foods as a source of amino acids
• Conversion of predecessor-proteins (proenzymes, zymogens, prehormones) into their final structures.
• Degradation of unneeded or damaged proteins for example cyclins at different stages of the cell cycle.

Proteolysis is also used in research and diagnostic applications:

• In-gel digestion of proteins after separation by gel electrophoresis for the identification by mass spectrometry.
• Digestion of proteins in solution for proteome analysis by liquid chromatography-mass spectrometry (LC-MS).

Examples

Examples of serine proteases include:

• trypsin
• chymotrypsin
• elastase
• papain

Venoms

Certain types of venom, such as those produced by venomous snakes, can also cause proteolysis. These venoms are, in fact, complex digestive fluids that begin their work outside of the body. Proteolytic venoms cause a wide range of toxic effects,^[1] including effects that are:

• cytotoxic (cell-destroying)
• hemotoxic (blood-destroying)
• myotoxic (muscle-destroying)
• hemorrhagic (bleeding)

See also

• Proteolytic enzyme
• The Proteolysis Map
• PROTOMAP a proteomic technology for identifying proteolytic substrates
• Proteasome
• In-gel digestion

References

1. ^ Hayes WK. 2005. Research on Biological Roles and Variation of Snake Venoms. Loma Linda University.

External links

• Proteolysis at eMedicine Dictionary
• Proteolysis MAP from Center on Proteolytic Pathways