Strange size of pET-22b expression product

Mikael Niku mikael.niku at
Thu Feb 26 07:18:14 EST 2004

> periplasmic prep. I suspect the periplasmic prep will contain both
> and unprocessed protein species and will show 2 bands on the SDS-PAGE,

This is in actually the case with an extracellular construct: two bands in
the periplasm, one (smaller) in medium.
With the cytoplasmic construct, I only see one band (I guess this is
somewhat logical, see below).

> By the way, do you see a lot of protein excreted into the media?

With the cytoplasmic construct, it's mostly in the medium. A significant
amount is also in the periplasm. But in fact I don't see much at all in
inclusion bodies (the extracellular constructs do more of this).

   Mikael Niku             URL:
   University of Helsinki  Dept. Basic Veterinary Sciences
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