Protease Inhibitor Selection: Avoid Protein Loss in Sample Prep

Protease inhibitors are valuable and useful reagents for researchers who want to inhibit general degradation of proteins in tissue or cell extracts by endogenous proteases. During isolation and characterization, proteases may pose a threat to the fate of a protein. Explore the different types of protease inhibitors and select the best one for your research.

• Classes of Proteases
• Proteases and Protease Inhibitor Cocktails

Classes of Proteases

Proteolytic cleavage of peptide bonds is one of the most important mechanisms affecting the properties of proteins. Proteases are ubiquitously distributed in all tissues and biological fluids. They are involved in a multitude of physiological processes ranging from functional activation or inactivation of proteins to their complete dissolution to simple amino acids. Four main classes of proteolytic enzymes are routinely utilized to describe proteases:

• Serine Protease Class includes trypsin, chymotrypsin and elastase.
• Cysteine Protease Class includes papain, calpain and lysosomal cathepsins.
• Aspartic Protease Class includes pepsin and rennin
• Metallo-protease Class include thermolysin and carboxypeptidase A

During isolation and characterization, one or all four classes of proteases may pose a threat to the fate of a protein. Broad spectrum protease inhibitors and cocktails (mixtures) have been developed to protect the integrity of proteins against multiple classes of proteases.

Proteases and Protease Inhibitor Cocktails

Protease inhibitor cocktails have been developed to safeguard the integrity of proteins during extraction and purification, to protect proteins during sample prep. Small molecule inhibitors also offer a powerful approach to identify and study the involvement of proteases in both normal physiological and pathological processes both in cell culture in vitro and in animals in vivo. We offer a broad range of well-established individual protease inhibitors and protease inhibitor cocktails that are optimized to maintain and preserve protein functionality following cell lysis. This offering includes:

• Various formats including powder, solution, or tablet
• Protease inhibition in almost any sample type (tissue or cell)
• Specific formulations optimized for particular applications
• Well-known brands such as:
  • SIGMAFAST™ inhibitors
  • ReadyShield^® inhibitor cocktails
  • Roche’s cOmplete™ protease inhibitor cocktail tablets
  • Calbiochem^® high-quality small molecules that potently inhibit a broad-spectrum of proteases

Click below to go to your protease inhibitor of interest and find what you need to enhance your sample prep.

• Protease Inhibitor Cocktails
• Calpain Inhibitors
• Collagenase Inhibitors
• Matrix Metalloproteinase Inhibitors
• Proteasome and Ubiquitination Pathway Inhibitors

Protease Inhibitor Cocktails

See how to differentiate our protease inhibitor cocktails by sample type, specificity, and more in the table below.

Calpain Inhibitors

Calpains belong to a family of calcium-dependent thiol-proteases that proteolyze a wide variety of cytoskeletal, membrane associated, and regulatory proteins. Over-expression of calpains has been positively linked to both acute and chronic neurodegenerative processes including ischemia, trauma, and Alzheimer’s disease. Calpain proteolysis is usually the late-stage common pathway towards cell death induced by excitotoxic compounds; hence, a selective inhibition of calpains by calpain inhibitors to limit neuronal damage is something of interest to research.

Collagenase Inhibitors

Mammalian collagenases belong to the family of metalloproteinases that specifically cleave collagen. Collagenases are produced by macrophages, fibroblasts, and keratinocytes that are involved in the wound-healing process. However, in chronic non-healing wounds and ulcers, there may be impairment of endogenous collagenase production leading to insufficient removal of dead tissue. Collagenases also play an important role in separating cells from their anchors. They dissolve desmosomes and thereby enable cells to migrate on a matrix of fibronectin. Explore collagenase inhibitors below.

Matrix Metalloproteinase (MMP) Inhibitors

The proteolytic degradation of the extracellular matrix (ECM) by tumor cells requires the action of highly specialized MMPs that are expressed in cell- or tissue-specific patterns. MMPs also play an important role in wound healing, angiogenesis, embryogenesis, and in pathological processes such as tumor invasion and metastasis. A major control point in the regulation of active enzyme is inhibition of the active form by the TIMP family of inhibitors (21-28 kDa). TIMPs regulate the function of MMPs either by inhibiting active MMPs with MMP inhibitors or by controlling their activation process. 

Proteasome and Ubiquitination Pathway Inhibitors

Proteasomes are large multi-subunit complexes, localized in the nucleus and cytosol that selectively degrade intracellular proteins. A protein marked for degradation is covalently attached to multiple molecules of ubiquitin. Several distinct groups of compounds, designed to act as selective proteasome inhibitors, have helped immensely in understanding the biological role and importance of the ubiquitin-proteasome pathway. These compounds are designed to block proteasome function in cancer cells without significantly affecting biological processes in the normal cell.