and don't forget to check diffraction without freezing. Mark On 15 April 2010 10:37, Anastassis Perrakis <a.perra...@nki.nl> wrote:
> Hi - > > My two cents: > > First, you say: > > I assume the bigger crystal might have lot of solvent which prevent for > high resolution. If it is true what could be the best way to dehydrate > crystal without affecting crystal quality? > > > I think this assumption is confusing. If the crystals were grown in the > same drop/condition, they have identical percentage solvent content. Thus, > you do not want to look at dehydration, the 'percentage solvent content' is > fine. What you want to look at is the mechanics of vitrification. Big > crystals, are simply hard to freeze: because of their volume they cannot be > vitrified as rapidly and uniformly as smaller crystals. I will not be > surprised if there are papers that quantify that, but what I am saying here > is only from experience and adding a 'logical' explanation to that > experience. > > Thus, I would simply stay with the smaller crystals (I have a feeling that > you 'small' crystals are 'big' for many other people) and be happy they > diffract to 2.5 A (is that SR or RA?) > > A. > > > On Apr 15, 2010, at 3:16, syed ibrahim wrote: > > > Dear Jurgen and Ho Leung > > To add few more point regarding my question: > > 1. Crystal was first frozen in LN2 and then transfered to cryo stream (in > presence of LN2 in vial) > 2. Anealing did not help (both short time and long time) - perhaps the > crystal dies. > 3. Spots are clear to available resolution (is: 6-7A). In the high > resolution region there is no spot but looks like smear in the whole area. > 4. The crystal was approximately 1.0mm length and 0.4mm dia. I mounted on > 0.5mm loop. So the liquid around the crystal was very less. I deliberately > avoided more solvent in the loop to help diffraction. > > Thanks > > Syed > > > > --- On *Thu, 4/15/10, Jürgen Bosch <jubo...@jhsph.edu>* wrote: > > > From: Jürgen Bosch <jubo...@jhsph.edu> > Subject: Re: [ccp4bb] Cryo Vs crystal size > To: CCP4BB@JISCMAIL.AC.UK > Date: Thursday, April 15, 2010, 3:46 AM > > There are a couple of additional factors not taken into account here. > > 1. LN2 versus frozen in strem or propane etc > 2. did you try to flash anneal the larger crystal > 3. smeary diffraction from the big crystal or not ? > 4. how much residual solvent was around your crystal when freezing ? > > In general smaller crystals are anyhow better in my hands. > > Jürgen > > On Apr 14, 2010, at 5:36 PM, syed ibrahim wrote: > > Hi All > > I had two crystals grown in same well, one is small and other is 10 times > bigger. I treated both crystal in same cryo and same time. The smaller one > diffracted to 2.5A and the bigger one to 6-7A. I was expecting the bigger > one to diffract high resolution. > > I assume the bigger crystal might have lot of solvent which prevent for > high resolution. If it is true what could be the best way to dehydrate > crystal without affecting crystal quality? > > Thank you > > Syed > > PS: Taken care of less solvent to be present in the loop > > > > > - > Jürgen Bosch > Johns Hopkins Bloomberg School of Public Health > Department of Biochemistry & Molecular Biology > Johns Hopkins Malaria Research Institute > 615 North Wolfe Street, W8708 > Baltimore, MD 21205 > Phone: +1-410-614-4742 > Lab: +1-410-614-4894 > Fax: +1-410-955-3655 > http://web.mac.com/bosch_lab/ <http://web.me.com/bosch_lab/> > > > > *P** **please don't print this e-mail unless you really need to* > Anastassis (Tassos) Perrakis, Principal Investigator / Staff Member > Department of Biochemistry (B8) > Netherlands Cancer Institute, > Dept. B8, 1066 CX Amsterdam, The Netherlands > Tel: +31 20 512 1951 Fax: +31 20 512 1954 Mobile / SMS: +31 6 28 597791 > > > > > -- Mark J van Raaij http://webspersoais.usc.es/mark.vanraaij http://www.ibmb.csic.es
