various protein A resins - difference in labolatory practice

[Dr Engelbert Buxbaum]

Am 03.05.2007, 23:18 Uhr, schrieb DK <dk from no.email.thankstospam.net>:


>>> Btw: For applications like immunoprecipitation you don't need the gel
>>> coupled to the purified protein A. Instead, use killed bacteria  
>>> expressing
>>> the protein on their surface. Calbiochem for example floggs that as
>>> "Pansorbin". Much cheaper and works just as well.
>>
>> It can be dirtier, as well, but some of that can be overcome by pre-
>> absrobing the lysate with Pansorbin first.
>
> What happens to proteins in those bugs when you elute IPs with
> loading buffer? That's the reason I was always hesitant to try Pansorbin.

Nothing. Killing is achieved with formaldehyde, which cross-links proteins.

In addition of course the proteins to be immuno-precipitated are usually  
labelled, e.g. from cells grown in 35-S Cys/Met. Since the bacterial  
proteins are unlabelled they would not interfere with your assay anyway.