Proteolysis is the directed degradation (digestion) of proteins by cellular enzymes called proteases or by intramolecular digestion. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins A protease is any Enzyme that conducts Proteolysis, that is begins protein Catabolism by Hydrolysis of the Peptide bonds that link

Contents 1 Purposes 2 Examples 3 Venoms 4 See also 5 References 6 External links

Purposes

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

• Removal of N-terminal methionine residues after translation. The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or Methionine ( abbreviated as Met or M) is an α- Amino acid with the Chemical formula HO2CCH(NH2CH2CH2SCH3 Translation is the first stage of Protein biosynthesis (part of the overall process of Gene expression)
• 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. A signal peptide is a short (3-60 Amino acids long Peptide chain that directs the post- translational transport of a Protein. The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer A virus (from the Latin virus meaning Toxin or Poison) is a sub-microscopic infectious agent that is unable Messenger ribonucleic acid ( mRNA) is a molecule of RNA encoding a chemical "blueprint" for a Protein product In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this A zymogen (or proenzyme) is an inactive Enzyme precursor. A zymogen requires a biochemical change (such as a Hydrolysis reaction revealing the A zymogen (or proenzyme) is an inactive Enzyme precursor. A zymogen requires a biochemical change (such as a Hydrolysis reaction revealing the A prehormone is a biochemical substance secreted by glandular tissue and has minimal or no significant biological activity but it is converted in peripheral tissues into an active
• Degradation of cyclins at different stages of the cell cycle. Cyclins are a family of Proteins involved in the progression of cells through the Cell cycle. The cell cycle, or cell-division cycle, is the series of events that take place in a eukaryotic cell leading to its replication

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. The in-gel digestion is part of the sample preparation for the mass spectrometric identification of Proteins in course of proteomic analysis. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Mass spectrometry is an analytical technique that identifies the chemical composition of a compound or sample based on the Mass-to-charge ratio of charged particles
• Digestion of proteins in solution for proteome analysis by LC-MS. Proteomics is the large-scale study of Proteins particularly their structures and functions.

Examples

Examples of serine proteases include:

• trypsin
• chymotrypsin
• elastase

Venoms

Certain venoms, such as those produced by venomous snakes, can also cause proteolysis. Trypsin ( is a Serine protease found in the Digestive system, where it breaks down Proteins Trypsin predominantly cleaves peptide chains at the carboxyl Chymotrypsin (bovine γ chymotrypsin,) is a digestive enzyme that can perform Proteolysis. In Molecular biology, elastase is an Enzyme from the class of Proteases (peptidases, that break down Proteins Forms and A snake is an elongate Reptile of the suborder Serpentes Like all reptiles snakes are covered in scales. These venoms are, in fact, highly-evolved 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

• Proteasome
• In-gel digestion

References

1. ^ Hayes WK. Cytotoxicity is the quality of being toxic to cells Examples of toxic agents are a Chemical substance, an Immune cell or some types of Venom Hemotoxins, haemotoxins or hematotoxins are Toxins that destroy Red blood cells (that is cause Hemolysis) disrupt Blood Myotoxins are small basic Peptides found in Snake venoms such as in that of certain Rattlesnakes This involves a non-enzymatic mechanism that Bleeding, technically known as hemorrhaging / haemorrhaging (see American and British spelling differences) is the loss of Blood from Proteasomes are large Protein complexes inside all Eukaryotes and Archaea, as well as in some Bacteria. The in-gel digestion is part of the sample preparation for the mass spectrometric identification of Proteins in course of proteomic analysis. 2005. Research on Biological Roles and Variation of Snake Venoms. Loma Linda University.

External links

• Proteolysis at eMedicine Dictionary

eMedicine is an online clinical medical knowledge base that was founded in 1996 by Scott Plantz and Richard Lavely two medical doctors

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