expressed protein is 5-6kda bigger than

[Christoph H. Winter]

>> In our workgroup this was found as well!
>
>Why?

Sorry, I can¹t explain it exactly...

In our group it was detected on a SDS-gel with a His-tagged scFv (should
have 28 kD by calculation, showed ca. 33 kD) and a non-related smaller
protein my colleque cloned. Maybe(!) it¹s caused by the positive charge
the His carries, retarding the whole protein...?

I don¹t know about proteins with a high amount of lysins and/or arginins,
maybe they behave similar.



BTW:
Citation of the QIAexpressionist, Appendix B:
³Some proteins with 6xHis tags attached run more slowly on SDS gels than
equivalent untagged proteins, and may appear to be several kD larger than
expected²



Bye

Christoph