Thankfully, there are ways to foil the action of these proteases. You can either keep your samples cold or use protease inhibitors to prevent the degradation of your protein sample. Better yet, you can use a protease inhibitor cocktail to effectively inhibit protease action.
Protease Inhibitors
Basically, there are four main classes of proteolytic enzymes - serine proteases (trypsin, chymotrypsin and elastase), cysteine proteases (papain, calpain and lysosomal cathepsins), aspartic proteases (pepsin and rennin) and metallo-proteases (thermolysin and carboxypeptidase A). Any one or all of these enzymes may pose a threat to the fate of your target protein during isolation and characterization. This is specifically why you need to add a protease inhibitor to the mix.
Protease inhibitors are valuable chemical tools that are used to prevent the degradation of proteins in tissue or cell extracts caused by endogenous proteases. In addition, these reagents can also be used to investigate particular processes that involve blocking the activity of specific proteases. Some of the most common protease inhibitors include AEBSF, aprotinin, bestatin HCl, chymostatin, leupeptin, pepstatin A, PMSF, and chelating agents such as EDTA and EGTA.
Unfortunately, there is no single protease inhibitor that can inactivate every known protease so you may need to consider using a protease inhibitor cocktail to protect the integrity of your protein sample.
Protease Inhibitor Cocktails
Broad spectrum protease inhibitors and mixtures, also known as Cocktails, are optimized to inhibit the action of harmful proteases while maintaining and preserving the functionality of your protein. By utilizing a specific combination of protease inhibitors, you can effectively protect the integrity of your protein samples during extraction and purification.
While some researchers prefer to prepare the appropriate cocktail by themselves, some prefer using a pre-formulated cocktail made by a reputable company instead. Here are the main reasons why most researchers choose commercially available protease inhibitor cocktails:
Tips in Choosing the Right Protease Inhibitor or Cocktail
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