Strep tag is very good for one step affinity purification of proteins in my experience it provides better results than His-tag. The high specificity of the resin helps to remove all the contaminant. The protein of interest is then eluted with 5mM d-Desthiobiotin buffer. Both the resin/hi-trap column and the d-Desthiobiotin are quite expensive but worth it.

Domenico Sanfelice Thank you so much. Is it suitable for proteins ranging from 40-60 kDa? How much concentration can you expect with this type of purification?

I used it for protein up to 100kda but I'm sure in literature you can find bigger proteins. Depending on your level of expression you can purify mg of protein.

Domenico Sanfelice Thanks a lot!