Hi,
You're probably referring to the Superdex 5/150 Tricorn column, with working
volume of 3ml, and not the 15/150?
Those columns work quite nicely for small sample volumes. For analytical
runs 15-25ul injection is pretty nice. The PC columns are originally
designed to be used with the SMART
For what it's worth, we've been using thermofluor to compare the 'apparent'
melting points of enzymes with their thermal stability measured as
inhibition of their respective reactions by elevated temperature. The data
so far make sense - the differences in apparent enzyme Tm (using the same
Destain it really well. One easy peasy option is to put the gel in water and
add 1 or 2 ml of cheap Q sepharose to it then boil. Gel will destain in 2-3
minutes of boiling.
On Sep 16, 2011 5:10 AM, K Singh ksc...@gmail.com wrote:
Dear All,
Can anyone suggest me a protocol for silver-staining the
1 imidazole affinity is not high which is why you use 200 mM or more to
elute. So it comes off by itself.
2 you can wash with low ph and then recharge this is somewhat easier on the
resin
On Sep 15, 2011 9:25 PM, m zhang mzhang...@hotmail.com wrote:
Dear all,
I have two questions:
First, I
trick I hadn't heard of before!
From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of
Artem Evdokimov
Sent: Friday, September 16, 2011 10:27 AM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] Silver staining Coomassie stained gels
Destain
one molecule of 37 kDa with solvent content 17%
I highly doubt it. It's theoretically possible, but with extremely low
solvent content like this the crystals should be tightly packed, with
all the consequences of tight packing such as higher resolution
diffraction and most of the bits accounted
I would not rule out pure chance. Crystals of the same protein can and often
do grow in two (or more!) different forms, from 'the same conditions' and
often in the very same drop. In this case it's the same space group, but
presumably different cell dimensions? Until a significant number of
favorite references :)
On Sun, Jul 10, 2011 at 10:58 PM, Artem Evdokimov
artem.evdoki...@gmail.com wrote:
I would not rule out pure chance. Crystals of the same protein can and
often do grow in two (or more!) different forms, from 'the same conditions'
and often in the very same drop
Could be a hexacoordinated cobalt with a water molecule (or a hydroxyl ion)
depending on the chemical environment...
Artem
On Thu, Jul 7, 2011 at 10:07 AM, Machius, Mischa Christian
mach...@med.unc.edu wrote:
Y'all,
I was wondering if anyone had any thoughts about a feature we observe with
There are about 20 structures solved by NMR with chain lengths above 300
residues. Some of them are solved by combination of restraints and modeling
(e.g. 2010 Nature paper describing implementation of Rosetta modeling
coupled with backbone-only data, by Raman/Montelione/Baker et al.).
Principal
Hey :)
Tubulin has high affinity towards colchicine. You may be able to subtract it
via colchicine-agarose if you can get some, or have some of it made.
Alternatively, merely adding colchicine may be enough to break the complex
between tubulin and whatever it is you're purifying (is it a kinase
As a follow up to the excellent suggestions made by others I would suggest
that a close examination of x-file headers may reveal abnormalities in e.g.
crystal orientation -- suspecting an unlocked or drifting goniostat. It may
also indicate a precession around the phi, which should also manifest
1) you can calculate the approximate unit cell parameter(s) from the spots.
I am guessing they will come out at 6-12 A (hard to tell from your image w/o
actual distance, wavelength etc).
2) this seems to be a diffractogram of a crystal stack where about a dozen
or two of thin plates are stuck
Check the PDB - looks like you defined them as C rather than Cl somehow.
Check their temperature factors, I bet they're way lower than the rest of
the ligand.
Also the arginine residue in the top left corner seems to be mis-modeled -
there's a water molecule where its end should be (and a nice
Technologies)
[image:
signature_crystalchall]http://www.chem.agilent.com/en-US/Products/Instruments/X-raycrystallography/Pages/Crystalchallenge.aspx?cid=4710
*From:* Artem Evdokimov [mailto:artem.evdoki...@gmail.com]
*Sent:* 19 April 2011 02:50
*To:* WINTER,MARCUS (A-UnitedKingdom,ex1
My vote is for His-tag *unless* your protein is of the same general class as
Zn-fingers, B-boxes, etc. (weak/multisite/uncertain metal binders) - these
proteins often do not fare too well with His-tags because a) the tag
residues can participate in artefactual metal-binding sites and b) the use
of
Hi,
So what's your secret - how did you pack an entire synchrotron into a little
box?
OK, so I am being facetious a little. However, I cannot help asking myself
why would I want to spend so much money on a system that is basically a
(vertical) X-ray diffractometer in a box, with fixed distance,
TCEP relies on a completely different chemistry to achieve the same goal as
BME or DTT.
DTT/BME use S(-)SS with redox potentials of -0.26 to -0.33 V (at pH 7)
whereasTCEP uses P(3+)-P(5+) oxidation with redox potential that's a lot
higher (I don't know of a reference with a stated redox potential
On Sun, Apr 17, 2011 at 2:14 PM, Nian Huang huangn...@gmail.com wrote:
Thank you for such great explanation. Hopefully people won't consider me
hijacking this thread.
Nian
On Sun, Apr 17, 2011 at 11:08 AM, Artem Evdokimov
artem.evdoki...@gmail.com wrote:
TCEP relies on a completely
For starters, you could re-clone the protein with e.g. just a His tag or
move the tag to another end, or put some distance between the end of TEV
site and the protein; or perhaps use no tag at all -- or a different one?
Is it possible that the tag is messing you up - yes. Is it 'probable' - I
I am too poor to afford cheap things
(I am not sure where quote comes from but it's relevant).
The answer depends on whether time is considered expensive or not. Sometimes
(e.g. when free labor such as graduate students) time is not an issue. And
sometimes it is. Reagent costs are fairly low now.
Try fitting a xylitol molecule in it but watch out for the distortions
caused by proximity to symmetry axis.
Artem
On Thu, Mar 31, 2011 at 1:16 PM, Shu XU xushuh...@gmail.com wrote:
Hi, there.
I'm refining a 1.76 A structure. The r-work stuck at 21%, rfree is 24%
after adding waters.
But
This can be very hard to do because quite a few proteases are promiscuous
and will cut substrates solely based on masking of the polypeptide within
the structure of the protein. Typically these proteases will not stop
cutting at a single nick - they often proceed until they can't 'dig into' a
1) Make your own with in vitro transcription (straight T7 r T7+RDRP like in
Finnzymes kit)
2) Buy from IDTDNA - they are very good
Long RNA tends to be expensive. Consider RNA ligase if two or more pieces
can be stitched together.
Artem
On Sun, Mar 13, 2011 at 3:39 AM, Michael Thompson
I absolutely *love* our Formulator. Bless its little white socks.
Artem
On Fri, Mar 11, 2011 at 4:46 PM, Stephen McMahon s...@st-andrews.ac.ukwrote:
Hi again,
Just for clarification.
The robot we are looking for will only dispense solutions for creating
optimisation screens.
No protein
Friends,
I would like to draw your attention to the announcement below.
Informal inquiries are welcome (directed to me) however actual applications
should be directed to the web site listed in the announcement (use
requisition number 003Y4 to find the position and apply).
Thank you for your
calibration.
Artem
On Sun, Feb 20, 2011 at 2:21 PM, Filip Van Petegem
filip.vanpete...@gmail.com wrote:
But this wouldn't correspond to a globular form; 250kDa DNA will appear
larger than a 250kDa globular protein.
On Sat, Feb 19, 2011 at 5:25 PM, Artem Evdokimov
artem.evdoki...@gmail.com wrote
A sufficiently long piece of DNA works OK.
On Sat, Feb 19, 2011 at 6:47 PM, Alexandra Deaconescu
deac...@brandeis.eduwrote:
Dear ccp4bb enthusiasts:
A question unrelated to ccp4: can anyone recommend a good 250 kDa standard
for gel filtration that is commercially available? It could be a
Mini-S is not quite what you're looking for. It's 3uM particles and has a
nice fat back pressure. Resource S-15 and Resource S-30 (with 15uM and 30uM
average particle size) may be what you need.
You may also want to take a look at monolithic columns because they develop
a lot less back pressure
'White' LED light produced by most integrated white LED packages is in fact
a mixture of blue (~460nm), produced by the LED itself and a
broad-band yellow (560nm), produced by a secondary phosphor, typically
directly coating the semiconductor that emits the primary light. The net
effect is a
Each protein is different, but there are indeed similarities within classes.
It can be dangerous/unproductive to generalize -- you will find out
experimentally whether you can assume things or not.
Depending on the expression method and the design of your construct you may
or may not have a tag.
http://shelx.uni-ac.gwdg.de/~tbeck/papers/mad_triangle.pdf
is the paper where the 'I3C' designation originates. I also recommend
Dauter's papers on halide phasing - very instructive stuff there.
5-Amino-2,4,6-triiodoisophthalic acid as such is not supposed to be
chemically reactive under
Tom,
What residues are being phosphorylated - S/T or Y?
You can take the phosphates off after/during purification but it is in fact
easier to take them off while they're being put on (i.e. by expressing the
kinase in E. coli that is already expressing a phosphatase). This tends to
work much
Use Urea - it does not interfere with gels etc. Additionally, you should
consider covalent immobilization of protein X - using activated resins.
Amine and carboxylic acid immobilization is common, however my all-time
favorite is iodoacetamide-activated resin reacting with SH on the protein
(if you
It depends on how your system is configured - primary considerations being
tubing length and tubing inner diameter (AKTA can come with at least three
different PEEK tube diameters, depending on what you purchased it for). New
systems often arrive with at least one tube-change kit (i.e. pre-cut
Hi,
You're working with a very 'rich' crystallization condition. It probably was
supersaturated or close to super-saturated with respect to something, and
that something crashed out on the surface (where liquid contacted air)
forming a crust. Your loop (while perfectly clean) can also be the
Depending on the type of resin you should be able to use IMAC all the way up
to pH 11 or so (works for Ni-NTA, not sure about HIS-SELECT or other
resins). Obviously your buffer system changes (carbonate works well at 11).
Why not to elute the complex together with pure monomer and then try
Hi,
I've seen soluble aggregates many times, with MBP and without. It's one of
the common outcomes of partially successful (sounds better than saying
'failed') expression attempts.
It is always possible to push further and try some fairly esoteric stuff
with E. coli if you're truly desperate,
FYI,
CCP4 release 2.0.6 does not seem to have 'SC' (a very useful program indeed)
in the list of programs in the GUI. This is on Linux (Generic)Fortunately,
the program itself is still included and is perfectly runnable from command
line old-school style :)
Artem
On Thu, Nov 11, 2010 at 3:57
I second the question of need: a decent PCR machine capable of
'thermofluor'-like experiments should cost around $34-$38K, which leaves
about the same amount of $$ for a decent purification machine. One of the
questions you have to figure out is: are you setting up a high-throughput
lab or a
Dear Sebastian,
Having personally purified upwards of 500 (I lost count really) of
His-tagged proteins, I can't say that I have the same awareness as you with
respect to the additional band being 'very common'. Depending on the kind of
expression system, size of your protein, conditions of
It's fun to watch my innocent little comment unfold into a pandemonium of
email :) That's why i love this mailing list.
Seriously though, there seems to be two salient things said by many people
in many different ways:
1. it's a good idea to look at the model in detail, and pay attention to
First piece of advice I have is to shove them in the beam and see what
happens. A few days ago we got high-resolution data from crystals that are
shaped like eggs. No edges on them whatsoever. In the past, saucer-shaped
crystals diffracted to 2A whereas their hexagonal 'perfect' cousins (grown
http://www.mail-archive.com/ccp4bb@jiscmail.ac.uk/msg04677.html
as well as some notes in the older posts :)
As a very basic rule of thumb, Rfree-Rwork tends to be around Rmerge for the
dataset for refinements that are not overfitted.
Artem
On Mon, Oct 25, 2010 at 4:10 PM, Rakesh Joshi
http://www.ruppweb.org/garland/gallery/Ch12/index_2.htm
br
*From:* CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] *On Behalf Of
*Artem
Evdokimov
*Sent:* Monday, October 25, 2010 6:36 PM
*To:* CCP4BB@JISCMAIL.AC.UK
*Subject:* Re: [ccp4bb] diverging Rcryst and Rfree
http://www.mail
In my hands GFP fusions can produce colorless crystals (but still have GFP!)
depending on the condition. Sometimes the crystals gradually become
colorless with time - bleaching or perhaps some chemical effect - no idea.
I've not tested the colorless crystals with UV to see if they still glow.
1)My protein has 14 cysteine residues.
That can be a big issue in itself :)
2)It is not a metal binding protein.
Are you sure, with this many Cys? Positive?
3)I have added the protease inhibitor cocktail + PMSF during sonication and
cleavage. I saw only one band of protein bind on
1. your information is helpful but not enough to tell if this double-band
pattern is a product of e.g. proteolysis or of abortive translation. You
don't specify what these 'minor differences' are - in the world of MS there
is no such thing as 'minor' since every difference is either a significant
NVIDIA NVS 3100M is an entry level card that mostly is designed with
'business applications' in mind - meaning that its
rendering/polygon/3D engine is relatively weak compared to an average
or even low-end modern desktop graphics cards. Nevertheless it is
definitely a step up from an integrated
Regardless of whether a system like this exists in Nature or not -
it's fun to imagine!
On a microscopic scale one could propose a hypothetical mechanism by
which a completely unfolded polypeptide chain could be fed into a
gated (or state-locked) peptidase that may break the chain down in a
PyMol
Pairwise superposition from Wizard menu.
Artem
On Fri, Sep 3, 2010 at 6:44 AM, Rex Palmer rex.pal...@btinternet.com wrote:
This is not really protein crystallography but we are trying to model build
a ligand into a protein binding site. A similar ligand is already in place
and we want
Yes, on both counts. SeMet proteins can be frustratingly* close to
their native forms - with little quirks like twinning or lack of
useful diffraction etc. It's common practice to micro (or macro) seed
with native crystals and it often works quite well. It's fun and
sometimes useful to add a few
Hi,
His-Select has been my favorite resin for IMAC for as long as Sigma's
been selling it. It's not the cheapest resin but at roughly $11/ml
packed bed volume and a capacity of ~10-20 mg protein per ml of resin
bed (depends on protein size, quality, and other factors) there seems
to be little
Pure diamond should do the trick.
Or you could try:
High-Quality Carbon-Doped Boron Nitride Membrane for X-Ray Lithography Mask
Akihiko Kishimoto, Masahiko Sakakihara1, Tetsurou Kawai1, Hiroaki
Oizumi, Shinji Kuniyoshi2, Sadae Yamaguchi3 and Kozo Mochiji
Central Research Laboratory, Hitachi,
1. look up Bacillus megaterium expression system (commercial, pretty
cheap relatively easy). It's easier to use than some of the
integration-based B. subtilis systems. Or you could ask around for a
suitable B.sut. shuttle vector as an alternative.
2. Bacillus codon set is heavily biased towards
It's called cross-soaking and it is a fairly popular technique
especially in the industrial community where we sometimes have to work
with hundreds of ligands.
I've done it on several occasions and mostly have been pretty happy
with the results. Having said this I also would like to point out
roughly judge whether your other peaks are garbage or
not.
Artem
On Wed, Jan 6, 2010 at 9:00 AM, Artem Evdokimov
artem.evdoki...@gmail.comwrote:
In addition to what the others have mentioned, if you're curious about
sigma levels to contour you may want to deliberately omit
an atom from your
Hello,
May the pouch of your Holiday Wombat overflow with presents!
I would like to draw your attention to a summer internship in our lab at
Monsanto. If you are an interested student, or know someone who may be
interested - please apply using
http://www.monsanto.com/careers/opportunities/ and
Dear Tiancen,
This is perhaps a more extreme example of what many of us have experienced
over and over - namely that for some proteins very small changes make a huge
difference in expression, solubility, activity or all three :)
Long and rambling reply follows - don't read if you are easily
Yes,
Ive methylated a ~300 kDa complex once, just for kicks and it still
functioned. MS was fairly good as well, showing that essentially all
accessible amines were altered. Notably I did not get the entire 300 kDa
complex on MS it did not survive TFA/Acetonitrile and I saw components
Artem Evdokimov wrote:
The angle value and the associated basic trigonometric functions (sin,
cos,
tan) are derived from a ratio of two lengths* and therefore are
dimensionless.
It's trivial but important to mention that there is no absolute
requirement
of units of any kind whatsoever
The angle value and the associated basic trigonometric functions (sin, cos,
tan) are derived from a ratio of two lengths* and therefore are
dimensionless.
It's trivial but important to mention that there is no absolute requirement
of units of any kind whatsoever with respect to angles or to the
Dear Sangeetha,
Can I assume that you detected the hairpin by computational means? In
general a single hairpin may not necessarily doom your experiment or reduce
expression - however you could reduce the hairpin stability via silent codon
changes just to be on the safe side. Keep in mind that
Hello Jacob,
I am not entirely sure why this has happened to you...
A couple of suggestions that may help:
1. dial down the TRIS to 20 mM - you can also use TRIS-HCl (unless the
second buffer is there for some other reason).
2. try a 'stronger' resin. I know in the past I've always strongly
Hi,
1. You can learn about compound binding using methods orthogonal to X-ray
(i.e. SPR, NMR, and so forth). If the sole detection method available to you
is X-ray then you should expect to need a reasonably complete dataset in
order to determine binding - otherwise you can easily miss binding
Dear Fabien,
Cases like that crop up from time to time. You shouldn't treat this peptide
in any way differently than any other peptide. If you're reasonably sure
about the peptide's sequence - BLAST it against a wide database (nr for
example). Like others pointed out, just make sure that it's not
and then
slowly coming off as NA get hydrolyzed or physically broken down.
Artem
_
From: megha goyal [mailto:mgbio...@gmail.com]
Sent: Friday, October 30, 2009 6:32 AM
To: Artem Evdokimov
Cc: CCP4BB@jiscmail.ac.uk
Subject: Re: [ccp4bb] Inclusion bodies centrifugation
Tried out
IB's precipitate in a few minutes at max. speed of tabletop Eppendorf.
Almost any speed above 5-6K in a larger rotor will precipitate them in 10-20
minutes, provided that the density of your IB wash is normal (i.e. you're
not using 70% sucrose, Renografin, or Cesium Chloride etc).
In other
Fragment based discovery is a fairly new but also fairly well established
technique. There is a difference between fragment screening and targeted
library screening, however notes below generally apply to both:
Libraries depending on what you want to discover you should try to obtain
a
Dear ccp4bb crowd,
Thank you for the wealth of useful replies to my request! I've received over
100 messages with suggestions!
A crude summary of replies is presented below (I've added PDB ID to most of
these). Overwhelmingly, the preferences tended towards iron-loaded proteins
(red or brown)
Hello felow MO crystallographer,
For all it's worth, a while ago I've compiled a little document which
describes mounting needles. I've converted it into PDF and posted it here:
Nothing is built on stone; all is built on sand, but we must build as if
the sand were stone
Jorge Luis Borges
I personally am not peeved at all, but I am getting concerned that most of
the jobs advertised are postdocs. Mighty and mysterious market forces have
cut very deep into the heart of structural science and this is not good.
Artem
Nothing is built on stone; all is built on sand, but we must
Dear Atul,
A question that any prudent structural biologist should ask sooner or later
once 'very tiny crystals' are obtained is - are these crystals made of my
protein of interest? I've witnessed at least three cases of 'tiny crystals'
being another (unintended) protein (confirmed by solving
Hi,
Part of the problem is that you are likely dealing with not just two
discrete conformations of the ligand (phenylpropanol by the looks of it) and
protein - there may be 'transition' states occupied below the level of
detection - therefore between the two 'end' states there's probably a
Stabilizing mother liquor is anything that (hopefully) will keep your seeds
'competent' (capable of nucleating single crystals). This may be anything
but typically what people start with is something on the lines of the well
solution supplemented perhaps with a bit extra precipitant.
As to
Hi,
Could you clarify your request a bit? Generally speaking if you allow the
ectodomain to have a membrane anchoring segment it will 'compromise'
solubility since the resulting protein most likely requires special
treatment (detergents) in order to be soluble. There's also the matter of
the
Hi,
Yes �C it’s quite likely that your protein is glycosylated. No worries,
it’s not a death knell �C in fact glycosylation can be interpreted as a
good sign :-)
Crystallization: yes, this may be an issue. On the other hand it could also
be not a problem. Try crystallizing the protein
You can always give this one a try:
http://www.xtals.org/crystal_cryo.pdf
Artem
Nothing is built on stone; all is built on sand, but we must build as if
the sand were stone
Jorge Luis Borges
_
From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of
Fengxia
Dear Scott,
If you're looking for rock-bottom prices I would try scouting a few used
equipment dealers. Also consider asking major brand sales people to quote
you for a 'floor model' or a 'demo model' - very often these are deeply
discounted.
With respect to brands - I personally have
Some proteins can be purified at room temperature. Others would be degraded
or may lose 'competency' (however you wish to define the latter). As a rule
of thumb, *most* proteins will not be hurt by exposure to +4C, but e.g.
detrimental protease activity should follow the normal kinetic rules and
Dear Ose,
This is unfortunately a fairly common issue. There are multiple ways to
rationalize what's happening - and even more approaches to reducing the
aggregation issues. It would take too long to list all the options here -
however I would look at the earliest stages of your expression and
Well, this is of course just my undereducated two cents but the first
question I'd ask is: asuming that dataset #2 is a real derivative - can I
find realistic sites? What are you basing your resolution cutoff on - in the
diffraction images, do you visually observe anisotropy?
It's not uncommon
Hi,
Hard to say w/o moving the thing around, but it could be: pep flips, or even
(less likely) wrong chain direction. Incidentally, some of thr the side
chains 'just don't look right to me' - interpret that one as you wish but
e.g. the leucine in the middle seems particularly wrong (try
Hi,
I am sorry that I cannot recall the highest concentration of DTT that I ever
used (inadvertently) when working with disulphide-containing proteins.
However I have the following mildly useful suggestion:
If you have properly formed -S-S- as well as a bunch of free -SH perhaps a
safer
Hi,
Since you're considering a serious undertaking, it would be good to know
whether your protein is decently expressed and reasonably characterized in
its native state - before advising you on the process :)
If your protein is normally expressed well, is soluble, and not aggregated -
there's
Hi,
1. do you know for sure that you have useful Se incorporation levels (i.e.
by MS)?
2. there are minimal distance constraints on how close heavy atoms may be
(one could use general chemistry knowledge to figure them out). Two actual
Se atoms should never be as close as 1A apart. The sites
What you're seeing is not necessarily pyrophosphate. The negative difference
density appears to concentrate around oxygen atoms most distant from the
protein (and perhaps around the putative phosphorous atom?). Some clues
might be obtained from e.g. the B-factor profile of the refined atoms. From
Those bubbles are mostly air - expelled out of the water by heat of mixing
(simple alcohols and water generate fairly huge heat upon mixing).
Crystalline sugars heat of mixing/dissolution is negative (which is why tea
gets cooler when you add sugar to it). Not sure what glycerol+water mixtures
do
Peter,
Depending on the method implemented in one software or another - I wouldn't
be surprised if some of them fall into local minima during gradient
optimization for best fit. Depending on how you define the region of
interest, there may also be ambiguity with respect to pair definition -
Jacob,
You should be able to get rid of the problem within a few days as long as
everyone in the lab is willing to cooperate.
Autoclaving works (it helps to use longer autoclave cycles - 40 minutes
instead of the regular 20).
If you confirm that phage is your issue - walk through the lab and
Identical is a very strong term - however if you're looking for 'very
similar' instead of identical then you should look at any kind of
extracellular receptor with Ig-like or Efhand-like domains - these often
look like choo-choo trains. Receptor-like phosphatases have similar
features. Another
Peter,
If I understand what you are saying - then it is very likely that your
protein forms aggregates. Whether this happens on concentration or not is
unknown because concentration may simply bring the pre-existing aggregates
to the membrane.
You can try to make concentration process
Yes,
This is 95% likely to be the dreaded T1 phage (well, OK - any lytic phage
that infects your culture, really). The almost-only other alternative is
that your protein lyses the cells.
Dealing with phage infection can be tough especially in the multi-user
environment and doubly so if you make
In addition to other excellent suggestions voiced here (insect cells,
refolding, etc.) you can attempt expression in constituitive mode - using a
mild always-on promoter. Provided that your protein is not too toxic to the
cells this may result in gradual accumulation of folded material rather
Kewl :)
I have one online but its ability to graph has been switched off because of
the inanity of my hosting provider. The source for the script (which also
calculates m.w. and extinction/absorption theoretical values) is here
http://www.xtals.org/prop_calc_script.perl
and the data file it reads
Yes :)
It's a common issue that requires a modicum of planning and dexterity to
overcome:
* cutting is done under a macroscope - it's much easier to see what you're
doing
* firm pressure on the plate (with one hand grasping the sides) is key to
success
* firm downward pressure of the
Looks like oxalate with two water molecules nearby. Oxalate is a fairly
common product of PEG oxidation.
Artem
---
When the Weasel comes to give New Year's greetings to the Chickens no good
intentions are in his mind.
-Original Message-
From: CCP4 bulletin board
Hi,
Since a surprisingly large number of people asked for the protocol, I
compiled a quickie PDF document and posted it here:
http://www.xtals.org/pdfs/iodination.pdf
Please excuse the inevitable consequences of haste - I am sure that the file
is riddled with spelling errors and poor grammar.
Try a non-auxotrophic method, in BL21(DE3):
http://www.xtals.org/pdfs/selenium.pdf
Artem
---
When the Weasel comes to give New Year's greetings to the Chickens no good
intentions are in his mind.
_
From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of
Kumar,
As many here have pointed out - this is not likely to work. However if you
already have crystals, why not to try phasing using tried and true heavy
atom derivatives. Who knows, you might get lucky and one of them might
actually improve the diffraction (this happens more often than
201 - 300 of 412 matches
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