The main difference between caspase and procaspase is that caspase is an active protease enzyme that is required in apoptosis or programmed cell death, while procaspase is an inactive protease enzyme and is the inactive precursor of caspase.
Proteases are a type of enzyme that catalyze the breakdown of peptide bonds in protein molecules. There are different types of proteases, including acid proteases, alkaline proteases, and neutral proteases. These protease enzymes exist in plants, animals, and microorganisms. Some proteolytic enzymes (proteases) are also available in supplements such as papain, trypsin, and chymotrypsin. Also, proteases involve in many biological processes, such as the breakdown of old proteins, cell signaling, and digestion of ingested proteins. Caspase and procaspase are two such proteases.
Key Areas Covered
1. What is Caspase
– Definition, Size, Function
2. What is Procaspase
– Definition, Size, Function
3. Difference Between Caspase and Procaspase
– Comparison of Key Differences
Key Terms
Caspase, Procaspase, Protease
What is Caspase
Caspase is a type of protease that plays an essential role in programmed cell death. These are endoproteases. They are a group of cysteineproteases.
Recent studies show that caspases also take part in other cellular remodeling events like spermatogenesis, erythroid differentiation, and cell fate determination. We call these proteases as caspases because of their specific cysteine protease activity (a cysteine in its active site attacks nucleophilically and cleaves a target protein only at the C -terminal of the aspartic acid amino acid). In fact, all caspases are produced as inactive zymogens. This is followed by a large and a small subunit.
The main enzyme that participates in apoptosis is caspase. Apoptosis is a complex process involving mechanisms in which many proteins participate. Activation of the caspases ensures the degradation of cellular components in a controlled way and performs cell death with minimal effect on the surrounding tissues. They also act as the main mediators of apoptosis. But excessive cell death is possible with the over-activation of caspase-3. This situation is prevalent in certain neurodegenerative diseases (for example, Alzheimer’s disease). Some other roles of caspases include aging, axon guidance, neural development, cell proliferation, cell differentiation, and suppression of tumors.
Furthermore, there are three functional subgroups of caspases in mammals. They are caspases that take part in inflammatory cytokine processing, apoptotic effector caspases, and apoptotic initiator caspases.
What is Procaspase
Procaspases are inactive precursors to caspases. They are inactive protease enzymes. They can be activated by cleaving one or two aspartic acids. Procaspase is cleaved into a large subunit and a small subunit, which is followed by dimerization. The large subunit and the small subunit associate with each other to make a heterodimer caspase. Moreover, two dimers combine to form a tetramer, which is activated as a caspase. An already-activated caspase triggers this process. However, procaspase, an inactive zymogen, can only be activated by an appropriate stimulus. Sometimes this activation process involves the oligomerization of procaspases. Moreover, there are different types of procaspases.
The activated enzyme generally exists as a heterotetramer in the biological environment. The dimerization step also aids the activation of initiator procaspase and inflammatory procaspase. Moreover, initiator procaspases cleave autoproteolytically. Moreover, the initiator procaspase cleaves the executioner procaspase.
Difference Between Caspase and Procaspase
Definition
Caspase is an active protease enzyme that plays a key role in apoptosis, while procaspase is an inactive protease enzyme and the inactive precursor of caspase.
Confirmation
Moreover, caspases usually exist as monomers or dimers, while procaspases exist as heterodimers or heterotetramers.
Size
Caspases are smaller molecules, whereas procaspases are comparatively larger molecules.
Function
Caspases help in tumor suppression, cell proliferation, axon guidance, aging, cell differentiation, as well as degrading cellular components in a controlled manner. On the other hand, procaspases form the active caspase enzyme after dimerization and cleavage to carry out the cellular function in programmed cell death.
Conclusion
In brief, proteases are enzymes that catalyze the breakdown of peptide bonds in proteins. There are many types of proteases, and caspases and procaspases are two such forms. The main difference between caspase and procaspase is that caspase is an active protease enzyme that is necessary in apoptosis, while procaspase is an inactive protease enzyme and is the inactive precursor of caspase.
Reference:
1. “Procaspase-3 Activation as an Anti-Cancer Strategy: Structure−Activity Relationship of Procaspase-Activating Compound 1 (PAC-1) and Its Cellular Co-Localization with Caspase-3” ACS Publications.
2. “Caspase – An Overview.” Science Direct.
Image Courtesy:
1. “Processing of procaspase-8” By Aina Estany – processing of procaspase-8 (CC BY-SA 4.0) via Commons Wikimedia
2. “Caspase-1 Zymogen” By Bilguudei Naranbaatar – Own work (CC BY-SA 4.0) via Commons Wikimedia
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