Cysteine protease

Source: Wikipedia, the free encyclopedia.
Cysteine peptidase, CA clan
SCOP2
1aec / SCOPe / SUPFAM
OPM superfamily355
OPM protein1m6d
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary

Cysteine proteases, also known as thiol proteases, are hydrolase enzymes that degrade proteins. These proteases share a common catalytic mechanism that involves a nucleophilic cysteine thiol in a catalytic triad or dyad.[1]

Discovered by Gopal Chunder Roy in 1873, the first cysteine protease to be isolated and characterized was

fig and kiwifruit. The proportion of protease tends to be higher when the fruit is unripe. In fact, the latex of dozens of different plant families are known to contain cysteine proteases.[2]
Cysteine proteases are used as an ingredient in meat tenderizers.

Classification

The

catalytic mechanism
.

For superfamilies, P indicates a superfamily containing a mixture of nucleophile class families, and C indicates purely cysteine proteases. superfamily. Within each superfamily, families are designated by their catalytic nucleophile (C denoting cysteine proteases).

Families of cysteine proteases
Superfamily Families Examples
CA
 C1, C2, C6, C10, C12, C16, C19, C28, C31, C32, C33, C39, C47, C51, C54, C58, C64,

C65, C66, C67, C70, C71, C76, C78, C83, C85, C86, C87, C93, C96, C98, C101

Homo sapiens)[5]
CD C11, C13, C14, C25, C50, C80, C84
Rattus norvegicus) and separase (Saccharomyces cerevisiae
)
CE C5, C48, C55, C57, C63, C79
adenovirus
type 2)
CF C15 Pyroglutamyl-peptidase I (Bacillus amyloliquefaciens)
CL C60, C82 Sortase A (Staphylococcus aureus)
CM C18 Hepatitis C virus peptidase 2 (hepatitis C virus)
CN C9
Sindbis virus-type nsP2 peptidase (sindbis virus
)
CO C40 Dipeptidyl-peptidase VI (Lysinibacillus sphaericus)
CP C97
Mus musculus
)
PA
 C3, C4, C24, C30, C37, C62, C74, C99 TEV protease (tobacco etch virus)
PB C44, C45, C59, C69, C89, C95
Homo sapiens
)
PC C26, C56
Rattus norvegicus
)
PD C46
Hedgehog protein (Drosophila melanogaster
)
PE P1 DmpA aminopeptidase (Brucella anthropi)
unassigned C7, C8, C21, C23, C27, C36, C42, C53, C75

Catalytic mechanism

Reaction mechanism of the cysteine protease mediated cleavage of a peptide bond.
See also: catalytic triad

The first step in the reaction mechanism by which cysteine proteases catalyze the hydrolysis of peptide bonds is de

carboxy-terminus of the substrate to the cysteine thiol is formed. Therefore, they are also sometimes referred to as thiol proteases. The thioester bond is subsequently hydrolyzed to generate a carboxylic acid moiety on the remaining substrate fragment, while regenerating the free enzyme.[6]

Biological importance

Cysteine proteases play multifaceted roles, virtually in every aspect of physiology and development. In plants they are important in growth and development and in accumulation and mobilization of storage proteins such as in seeds. In addition, they are involved in

tobacco etch virus protease
).

Regulation

The activity of cysteine proteases is regulated by a few general mechanisms, which includes the production of

zymogens, selective expression, pH modification, cellular compartmentalization, and regulation of their enzymatic activity by endogenous inhibitors, which seemingly is the most efficient mechanism associated with the regulation of the activity of cysteine proteases.[6]

Proteases are usually synthesized as large precursor proteins called

pepsinogen. The protease is activated by removal of an inhibitory segment or protein. Activation occurs once the protease is delivered to a specific intracellular compartment (for example the lysosome) or extracellular environment (for example the stomach). This system prevents the cell
that produces the protease from being damaged by it.

Protease

allosteric site
, which alters the active site and makes it inaccessible to the substrate.

Examples of protease inhibitors include:

Uses

See also: Papain § Uses, Bromelain § Uses, Ficain, and Chymopapain § Medical applications

Potential pharmaceuticals

Currently there is no widespread use of cysteine proteases as approved and effective

porcine acanthocephalan parasite Macracanthorhynchus hirundinaceus.[10] A useful property of cysteine proteases is the resistance to acid digestion, allowing possible oral administration. They provide an alternative mechanism of action to current anthelmintics and the development of resistance is thought to be unlikely because it would require a complete change of structure of the helminth cuticle
.

In several

infections both in humans and livestock
.

Other

Cysteine proteases are used as feed additives for livestock to improve the digestibility of proteins and amino acids.[11]

See also

References

  1. ^
    S2CID 234597200
    .
  2. PMID 18496785
    .
  3. PMID 5470818
    .
  4. PMID 24939387
    .
  5. PMID 2400579
    .
  6. ^
    S2CID 248741177
    .
  7. PMID 15448724
    .
  8. PMID 9074757
    .
  9. PMID 15193563
    .
  10. PMID 18761736
    .
  11. ^ O'Keefe, Terrence (6 April 2012). "Protease enzymes improve amino acid digestibility". Wattagnet. Retrieved 6 January 2018.

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=Cysteine_protease&oldid=1220788483"