Hi,
I'm an undergraduate student currently doing a one year research placement as part of my degree.
According to recent literature, a cytokine I'm working with is cleaved into a more active form by at least two serine proteases, but cleaved and inactivated by a cysteine protease. In order to obtain a native source of the cytokine, I culture a human cell line and then lyse the cells using multiple freeze-thawing cycles (the cells do not secrete the cytokine in question). I've found that adding a universal protease inhibitor cocktail to the culture during the freeze-thawing process greatly reduces cleavage of the cytokine (shown by IP) and its activity (measured using a reliable and well established reporter gene assay).
Now I would like to lyse the cells in the presence of inhibitors which only inhibit serine proteases, but I am unsure which ones to use, and how likely they are to inhibit the serine proteases I'm interested in (I can't find any specific inhibitors for these) while at the same time having minimal effects on the activity of other classes of proteases, particularly cytseine proteases.
