Dear Shraddha,

Two things to suggest.

1. the concentration of arsenic: You need to try different concentrations of arsenic (2 fold to 10 fold differences) to see the desired effect. and even the duration of induction is also important.

2. the sensitivity of your detection: you may not see subtle changes in the expression of proteins with normal staning protocols (I assume you are using coomassie staining). Use silver staining or other types of proteomic analyses, for example 2 D gel electrophoresis or mass spectrometry. However, I have gone through some literature, where, I could not see anybody doing SDS-PAGE. All of them studied expression at mRNA level. Please find the attached links.

I hope this will be helpful to you. Goodluck

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC206058/

http://jb.asm.org/content/185/18/5363.full.pdf+html

http://www.jbc.org/content/271/5/2427.full

Thank you so much for suggestions and papers Sir. 

Are you sure there are some arsenic-induced proteins in E. coli? How about arsenate instead of arsenite?

Hi there

How do you know there is induction of a change of protein profile with addition of arsenic in the first place.

If you just add more arsenic or leave it for longer incubation, you may just kill the cells.