Qiagen DNA purification resin - what is it?
krasel at wpxx02.toxi.uni-wuerzburg.de
Fri Aug 2 03:24:17 EST 1996
[fixed some attribution; followups to the cloners' group only]
I wrote some BS in my last posting (seems my brain was on vacation while
writing :-) I cancelled it. You will still find it in the archives :-(
Dima Klenchin (klenchin at macc.wisc.edu) wrote:
> In article <gjenkins-0108960831430001 at 126.96.36.199>,
> gjenkins at facstaff.wisc.edu (Glenn Jenkins) wrote:
> ->In article <4tlpbs$2hc4 at news.doit.wisc.edu>, klenchin at macc.wisc.edu
> ->(Dima Klenchin) wrote:
> ->> Just curious - what type of anion exchanger is it?
> ->> QAE? And what is the support made of? Simply can't believe
> ->> this is smth magic that qiagen developed. Must be some oldie
> ->> for which a new application was found.
> ->My understanding is that it is has charged groups (ie. DEAE?) attached
> ->to a silica matrix. These groups are attached in high density which allows
> ->a greater salt gradient to be used to elute the DNA. Thus you will have
> ->less overlap with proteins and RNA.
> ->I do not find a great advantage of their preps($$) except if I want
> ->pure DNA. Time wise is it not much of a savings either. One day when I
> ->have time I want to do the basic miniprep and apply the Na Acetate/DNA
> ->solution to a DEAE sepharose column to see what sticks. I suspect there
> ->will not be much of a difference.
> ->Does anyone else have any ideas?
> Well, DEAE for *NA purification has been used *widely* in "dark ages"
> (before all these fancy kit$). I'm still wondering what's that special
> about Qiagen's stuff. And, alas, there is no information on _type_ of
> exchanger in archives. Silica is the support? Great. That would mean that
> the resin should not been used below pH ~ 6.0 Is this true?
Some of the Quiagen blurb:
QIAGEN resin is a unique anion-exchanger with a hydrophilic surface
modification that selectively separates nucleic acids from other
substances, such as proteins, carbohydrates, metabolites, or dyes.
The macroporous anion-exchanger, with a particle size of approx.
100 um, has a hydrophilic surface coating containing DEAE groups,
creating an extremely high surface charge density. The large pore
size, together with the high density of anion-exchange groups,
provide the extraordinarily broad separation range that makes
QIAGEN resin unique.
The separation range of QIAGEN resin extends from 0.1 M to 1.6 M salt.
Conventional anion-exchangers, based on cellulose, dextran or agarose,
have separation ranges only up to 0.4 M salt. Binding and elution of
all substances is thus limited to a narrow range of salt concentrations.
As the elution peaks of proteins, RNA, and DNA overlap extensively
with one another, a satisfactory separation cannot be achieved.
QIAGEN resin will not function in the presence of anionic detergents
such as SDS, or at a pH less than 4.0.
I don't think their support is silica: Qiagen has been fairly quick
to sue competitors who use similar resins; however, they have apparently
not been able to sue Macherey & Nagel, who sell a similar kit (called
"Nucleobond") where the resin is derivatized silica. Also, the description
of the resin (the "hydrophilic coating") does not speak for silica.
The DNA from Qiagen columns in my experience is about as clean as DNA
from CsCl preps (but contains less salt). It's much less hassle, however.
Usual disclaimers apply. (I don't work for Qiagen. I don't get any
profit from this posting. I don't ... :-)
/* Cornelius Krasel, U Wuerzburg, Dept. of Pharmacology, Versbacher Str. 9 */
/* D-97078 Wuerzburg, Germany email: phak004 at rzbox.uni-wuerzburg.de SP3 */
/* "Science is the game we play with God to find out what His rules are." */
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