Curr Protoc Protein Sci. 2001 May:Chapter 21:Unit 21.1. doi: 10.1002/0471140864.ps2101s21.


The processes of growth and remodeling of cells and tissues in multicellular organisms require the breakdown of old protein molecules, in concert with the synthesis of new ones. For example, many newly-synthesized molecules require proteolytic processing to convert them to biologically active forms. Proteolysis can terminate the activity of a protein--e.g., capsases mediate apoptosis, which is a vital step in the life cycle of the cell. Proteolysis contributes to defense systems too, as the recognition of peptide fragments of foreign proteins triggers the immune response. Proteases are the class of enzymes involved in these important reactions. This unit discusses the general categories of proteases, and sets the stage for addition of overview units on cysteine proteases, aspartic proteases, and metalloproteases, as well as protocol units featuring techniques for analyzing mammalian and yeast proteasomes and protease inhibitors, among other topics.

MeSH terms

  • Animals
  • Aspartic Acid Endopeptidases / metabolism
  • Bacterial Proteins / metabolism
  • Catalysis
  • Cysteine Endopeptidases / metabolism
  • Humans
  • Metalloproteases / metabolism
  • Peptide Hydrolases / classification*
  • Peptide Hydrolases / metabolism*
  • Substrate Specificity
  • Viral Proteins / metabolism


  • Bacterial Proteins
  • Viral Proteins
  • Metalloproteases
  • Peptide Hydrolases
  • Cysteine Endopeptidases
  • Aspartic Acid Endopeptidases