Problem in Protein expression (in E.Coli)

Chii-Shen Yang c-yang at nwu.edu
Fri Nov 14 17:14:29 EST 1997


Hi, we encounter a big problem in protein expression using E.Coli
system.

The system worked fine for years.  We were able to express milligram
amount of His-tagged recombinant (alpha subunit of G protein) proteins
and purify it to homogenius state with Ni-column and then HPLC.

Recently (few months), we were not able to get proteins.  We suspect
bacteriophage infection in our culture could be the case. Here are some
observations;
1. Cells grow slower than usual and no lysed cells are observed in the
medium.
2. After freezing and thowing process, the cells often lyse.

Do you think those are symptoms of phage-infection as we suspect ?

If you have any expreience of this situation or you know how to deal
with bacteriophage infection, please let us know.

Any suggestion is greatly appreciated.

Happy study.

Chii-Shen Yang
c-yang at nwu.edu





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