Good description from Ian complemented by an amusing aside from Peter.
One small point. Ian says
"The answer is that it turns out that the equation ('Kramer-Kronig
relationship')
governing X-ray scattering is completely analogous to that governing
optical dispersion,"
Analogous implies the pheno
Dear all
Perhaps a bit off of theme, just an example about resolution cut-off
mean I/sigma(I) = 2 for dmin = 3.35 A
(please have a look at the attached pdf)
I would trust in I/s(I) = 2 (in this case it worked), but why not to
determine what is information after the model has been refined to
Are you close to the theoretical isoelectric point of your protein ? Change pH
of buffer
Jürgen
..
Jürgen Bosch
Johns Hopkins Bloomberg School of Public Health
Department of Biochemistry & Molecular Biology
Johns Hopkins Malaria Research Institute
615 North Wolfe Street, W870
P.S. I haven't personally tried concentrating with PEG 20K but I suppose
it could work.
On Sat, Jan 28, 2012 at 12:41 PM, Cale Dakwar wrote:
>
> Hello Rashmi,
>
> How large are your protein monomer units? Are you expecting these units
> to have formed an oligomer? As a general rule of thumb
Hello Rashmi,
How large are your protein monomer units? Are you expecting these units to
have formed an oligomer? As a general rule of thumb, you want your protein
molecules to be no smaller than 3x the membrane MWCO. Perhaps all you need
is to try concentrating with a lower MWCO membrane, e.g.
Dear Jacob,
As an editor I am always mindful that an article is finally under the
authors' names. That said the reader always deserves to know at what
diffraction resolution average intensities (cease to) exist. The usual
statistical practice to do that is to use a given quantity's (ie in
this case
Hi all,
I tried to concentrate my protein using vivaspin 20 10,000 MWCO PES.
The protein was in 50mM Hepes pH 7.5, 500mM KCl and 10% glycerol.
I lost about 90% of my protein on the membrane of the centricon.
Please suggest some way of concentrating this protein.
Will concentrating using peg 20K
Ian,
If you visit Isaac Newton's old home at Woolsthorpe (near here) you will
see a conflicting claim for location of the classic prism experiment. You
will also find an apple tree in the garden, but that is another story..
Peter
PS this is my special ccp4bb email account, it doesn't always g
Hi Jacob,
I think a lot of people do use I/sigma :o)
However sigma is in some cases poorly defined, and the merging
residuals you refer to are calculated only from the I values and are
related to I/sigma anyhow... Of course the R values are sometimes also
poorly defined for low multiplicity data.
