Biotin contamination of BSA

[Dr Engelbert Buxbaum]

Am 16.07.2009, 05:54 Uhr, schrieb WS <novalidaddress from nurfuerspam.de>:

> I noticed that "ordinary" BSA is unsuitable for blocking westerns when
> streptavidin HRP is used, as it causes high background by its biotin
> content. Where does the Biotin contamination come from and how may I
> get rid of it (except buying biotin free BSA)? Is it covalently
> linked?

Try fish skin (teleost) gelatin instead, or polyvinylpyrollidone (PVP). If  
you blot on PVDF membranes, you do not need to block at all. Air-dry the  
membrane completely, then all solutions can interact only with  
surface-bound proteins, but not with the very hydrophobic membrane -> no  
background binding.