Protease Inhibition and Detection Overview

By: Robert Gates Product Manager, BioFiles 2009, 4.2, 3.

BioFiles 2009, 4.2, 3.

Robert Gates
Product Manager
robert.gates@sial.com

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Proteolytic hydrolysis of peptide bonds was first studied as a function of digestion in higher mammals. It is now recognized as an essential and ubiquitous mechanism for the regulation of a myriad of physiological processes. Inhibition of proteolytic activity is usually employed for two purposes.

  • For the prevention of unwanted degradation of proteins during their isolation and characterization
  • To study the regulatory aspects of specific proteolytic events as they relate to cellular processes. Some of the most studied proteolytic processes include blood coagulation and complement cascades, hormonal regulation, apoptosis, extracellular matrix degradation, proteasome and lysozomal regulation, and disease states such as Alzheimer’s and viral replication.

Four main classes of proteolyic enzymes have been routinely utilized to describe proteases. The serine proteases are probably the best characterized. This class of proteases includes trypsin, chymotrypsin, and elastase. The cysteine protease class includes papain, calpain, and lysozomal cathepsins. Aspartic proteases include pepsin and rennin. Metalloproteinases 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 mixtures (or cocktails) have been developed to protect the integrity of isolated proteins. Sigma® offers and manufactures the broadest range of protease inhibitors and inhibitor cocktails of any supplier. Sigma inhibitor cocktails have been specifically formulated for particular applications as they relate to the biological source or method of expression.

Protease inhibitors can be added during cell growth and protein expression or can be added at the time of extraction.

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