Does a C-terminal Proline Residue Increase Degradation Risk? - (Nov/20/2013 )

I don't know if it is my fuzzy memory or not but I think that I've read that a recombinant protein that terminates in a proline residue is at an increased risk of degradation and subsequent apparent low yield.  Am I making this up or has someone else heard of this too.  I've been searching for a reference to confirm and haven't been able to come up with one.  I'm about to start a new recombinant project and the protein ends with a double proline residue.  I need to decide if I want to cap it in some fashion or if its not really necessary.

Thanks in advance for the help!

Hi Missle.  The decision to "cap" the protein will likely depend on your expression system, method of purification, and the activity of cleaved vs. uncleaved protein.  You could always start expressing the wild-type protein and determine along the way if protease activity is an issue.

Here is a paper I found about a protease that cleaves after a penultimate proline residue:http://www.pnas.org/content/95/7/3472.full.pdf

This might be what you were thinking of.

Thanks for the response & the reference!  It will be a bacterial expression with a N-terminal MBP fusion tag.  I don't do any PCR or cloning in my lab so we have the gene synthesized and clones so I need to avoid the need to go back and change the construct - if at all possible.....