Smallest mutatable catalitic or fluorescent protein

EK khatipovNO-SPAM at
Wed Nov 27 21:06:05 EST 2002

Hi everybody,

I would like to construct the following fusion:
Peptide1 ---Carrier(6His)protein ---Peptide2

Peptide1 is a 12-mer with variable sequence. Basically this is a library
that will be screened for activity towards a mammalian drug target protein.
Peptide2 is a protein transduction domain to be used for delivery of the
fusion into mammalian cells through the cell and nuclear membranes. The
carrier protein should have 2 functions: 1) be catalytically active,
fluoresce, or be otherwise labeled (autobiotibilated in E.coli, etc). for
quick intracellular detection purposes (= so that the fusion could be easily
quantitated in _mammalian_ cells using absorbency or fluorescence

The purpose of constructing the fusion is to be able to obtain many
different variants of fusion proteins by expression in E.coli rather than
spending too much money on chemical synthesis of the Peptide1-Peptide2

I know that one of the possibilities is to use GFP as such carrier protein,
because it is possible to insert 6His at e.g. Y143 without affecting folding
and fluorescence spectrum. However, GFP is too big, and I was looking for a
smaller protein that could serve as such a carrier.

Could someone come recommend such a carrier protein? Again, the important
thing that this protein can be used as a purification tag and as a lable.
Thanks for any feedback.


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