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Can anyone tell me why proteinase K doesn't degrade itself?

If possible please provide me the source.

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  • $\begingroup$ Are you asking about in vitro or in vivo? $\endgroup$
    – canadianer
    Oct 7, 2014 at 16:36

2 Answers 2

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According to invitrogen proteinase K does undergo autolysis, but that some leftover fragments still have protease activity. The solution should be stored at -20C, this low temperature is probably the best way to prevent autolysis. If you're using the enzyme to digest protein at 37C, you'll just have to deal with losing the proteinase k during the reaction and make sure you add enough to destroy the target protein before the proteinase is depleted.

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Proteinase K is sensitive for autolysis. The enzyme is stabilized by the presence of calcium ions (which bind to the protein). Absence of calcium promotes autolysis of the enzyme and also reduces the half life of the enzyme activity. The most likely reason why most researchers never notice an substancial effect of autolysis is that this takes around 48h to get noticed, while the most proteinase K digest take only a few hours. For details read the following paper:

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