Greg:
Ammonium ion is listed as a competitive inhibitor of Lys-C (Wako). Having said
that, I've used ammonium bicarbonate buffers with that enzyme many times with no
probems at all. Lys-C is one tough enzyme.
Likewise, an addendum to the discussion of trypsin activity in guanidinium
chloride: 2M GuHCl will surely kill trypsin, and lower amounts are likely to hurt
activity too. But the bottom line is yield of tryptic peptides from the protein
you want to digest. This is a function of many things, including the activity of
trypsin and the degree to which the substrate is denatured (exposing cleavage
sites). So a trade-off between activity and denaturation is sometimes
acceptable. I have had occasion to solubilize/reduce/alkylate uncooperative
proteins in 6M GuHCl and digest them with trypsin after dilution to below 1M GuHCl
- with good results.
Regards.
Dave
Greg Grant wrote:
> Dear Colleagues:
>
> The recent conversations regarding proteases has left me a little
> confused ( a natural state, some would say) and I have unfortunately
> deleted the correspondence.
>
> My question is, which proteases are inhibited by ammonium bicarbonate?
>
> Thanks,
>
> Greg
>
> Gregory A. Grant
> ggrant@pcg.wustl.edu
> 314-362-3367
> FAX 314-362-4698
This archive was generated by hypermail 2b29 : Fri Sep 01 2000 - 16:10:38 EDT