I prepared a solution of Pesin in 0,1M HCl and I stored it at -20ºC. Due to the concentration of pepsin that I need in this solution, I need to prepare a lot of solution in comparison to the amount that I need to use each time. As far as I know, HCl is activating Pepsin, do I need to prepare the solution every time I need to use it or by aliquoting it and storing it at -20ºC it is ok? Is pepsin loosing its activity when stored in HCl?
Dear Anna
Pepsin is quite stable at low pH. Please see an old [good] paper on this subject
http://www.jbc.org/content/234/12/3137.full.pdf
Ravi
Biology is not mathematics so do no trust very much what has been up to now reported as there should be a exception to a general rule. It can be applied to comercial or pure preparations but not neccessarily to crude extracts from biological material. The results depends not only on the enzyme but on the other components (buffers, estabilizers) and is critic with crude extracts (other proteins and biomolecules). By doing a simple experiment you can see by yourself, so go ahead. The key issue is how do you freeze and how do you thaw. It must be as quick as possible (freeze in liquid nitrogen) and thaw by inmersing in a bath at 25-30 ºC. It is possible you get precipitates, this depending, among others, of the protein concentration (dilute concentrations use to be less stable).
Hi Anna,
I have “P6887 SIGMA Pepsin from porcine gastric mucosa lyophilized powder, 3,200-4,500 units/mg protein” Do you know how can I make the stock? I will be very great full if you help me.
Thank you so much
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