Kd semantics

Dr Engelbert Buxbaum via methods%40net.bio.net (by engelbert_buxbaum from hotmail.com)
Mon Feb 18 15:07:08 EST 2008


Am 11.02.2008, 03:50 Uhr, schrieb <kaj.stenberg from helsinki.fi.invalid>:


> Just another thing: when can you start talking about a "real" (as in
> specific) affinity? I am reading papers with a Kd in the ballpark of
> tens of millimolar and find it hard to repeat the work so that I truly
> believe in the results, since every random event seems to affect the
> curves fairly much.

Remember that in order to get accurate results for binding studies both  
[E] and [S] should be in the same order of magnitude as Kd. Thus for Kd =  
1 mM -> [E] should be at least 0.1 mM (better several times more), and as  
you can calculate yourself that is quite a lot for a substance of say, M =  
50 kDa.


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