Re: Proteolytic enzyme to cleave at C-terminus of threonine

Richard Laursen (laursen@bu.edu)
Mon, 17 Aug 1998 16:04:59 -0500

It is also possible that the cleavage is due to some non-specific protease
(e.g., from a contaminating bacterium) that just happens to clip your
protein, which presumably was stored in its native form, at some exposed
loop. A classic example is ribonuclease, which is specifically cleaved at
Ala-20 by low concentrations of the-not-very-specific subtilisin. I
believe there are other cases of very specific fragmentations of proteins
during storage (I seem to recall an immunoglobulin example) due to
contamination. I think crystallographers run across this problem
occasionally with protein solutions that have to be kept at above freezing
temperatures for weeks.

Richard Laursen

>At 05:18 PM 8/17/98 +0900, Tatsuru_Sasagawa@trc.toray.co.jp wrote:
>>................ I have a strange experience that during storage,
>>our protein was cleaved at c-terminal of threonine. Are there such
>>enzymw with threonine specificity? ..............
>>tatsuru Sasagawa
>>Toray Research Center
>
>Tatsuru- The cleavage could as well have targeted the N-terminal end of
>the following residue.
>Regards,
>
>John Hempel, PhD Ph (412) 624 0161
>University of Pittsburgh FAX (412) 624 4759
>Department of Biological Sciences
>Pittsburgh PA 15260 email: hempel@psc.edu
> http://www.pitt.edu/~biology/faculty/hempel.html

Richard A. Laursen
Department of Chemistry
Boston University
590 Commonwealth Ave.
Boston, MA 02215
Tel (617) 353-2491; FAX (617) 353-6466
email: <laursen@bu.edu>