ZERO yield from Qiagen Maxi Prep

[vilimf01 at mcrcr6.med.nyu.edu]

In article <5c0fmt$anl$1 at oac2.hsc.uth.tmc.edu>, sa83207 at odin.mdacc.tmc.edu (Jennifer Philhower) writes:
> Ian A. York wrote:
> 
> I'd skip the "qiafilter" business and instead use the traditional
> centrifugation to clear out the precipitated SDS gunk.  I've done a number
> of side-by-side comparisons and consistently found that I got
> less--sometimes much less--DNA with the Qiafilters.  I've no idea why.
> ------------

It is the SDS. Using the filter, there is more SDS in the cleared
lysate, and it interferes with the DNA binding to the matrix.  I use
the filters, but only after the spin, to remove any of the floating
percipitate that never seems to spin down in my hands.  They are quite
handy for that, but not much else.

				Usual disclaimers	SVEN



> 
> I have found the same to be true with the Qiafilters in my hands.
> In my case, I think it has to do with the fact that in clearing the
> lysate, much is left behind in the filter cartridge, as the filter
> itself clogs with precipitate.  The volume of cleared lysate is 
> considerably larger when I spin instead.  
> 
> The filter does save a bit of time, and if I am in some sort of
> supreme hurry I will use it, but otherwise I follow the spinning
> protocol.
> 
> Jen (isn't he from afu?) Philhower
>