Re: [ccp4bb] Yet another "what's my blob" thread, part II

2017-10-11 Thread Lucas 
Oops, should have mentioned that - Cryoprotectant was PEG200, 20%.

Re: [ccp4bb] Yet another "what's my blob" thread

2017-10-02 Thread Roger Rowlett 
Blob one is something possibly distorted by alternate partial occupancy
binding sites near a symmetry axis. Blob 2 could be a chloride ion, or if
that is not enough density, maybe bicarbonate. Blob 1 seems to be attracted
two His residues, of the things in your mixture, Mg(II) seems possible or
Cl-. Blob 2 is less likely to be  metal around those Arg residues, but Cl-
or bicarbonate are possible and well-known in this kind of coordination
environment. Cl- is in your mixture, and bicarbonate can accumulate,
especially at alkaline pH from atmospheric CO2.

Cheers,

Roger Rowlett

On Oct 2, 2017 6:06 PM, "Lucas"  wrote:

I'm in the later stages of solving a structure which contains two
tetramers in the asymetric unit. I found these two blobs (in
equivalent positions on each tetramer) with positively charged
residues around it. Crystallization condition is Magnesium chloride,
Bis-tris and PEG3350. While the second blob looks like a metal, the
first one has a weird shape even though they are expected to have the
same thing. Any ideas?

Lucas

Re: [ccp4bb] Yet another "what's my blob" thread

2017-10-02 Thread Keller, Jacob 
Looks like it's at a symmetry/NCS axis, so that complicates appearances...

JPK

-Original Message-
From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Lucas
Sent: Monday, October 02, 2017 6:06 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: [ccp4bb] Yet another "what's my blob" thread

I'm in the later stages of solving a structure which contains two tetramers in 
the asymetric unit. I found these two blobs (in equivalent positions on each 
tetramer) with positively charged residues around it. Crystallization condition 
is Magnesium chloride, Bis-tris and PEG3350. While the second blob looks like a 
metal, the first one has a weird shape even though they are expected to have 
the same thing. Any ideas?

Lucas