From the two images, it appears there are two short cell axes and one long axis - it also looks like trigonal or hexagonal, then the long axis should be c. Of course lower symmetry with a nearly hexagonal-shaped cell can not be ruled out. Mark J van Raaij Laboratorio M-4 Dpto de Estructura de Macromoleculas Centro Nacional de Biotecnologia - CSIC c/Darwin 3, Campus Cantoblanco E-28049 Madrid, Spain tel. (+34) 91 585 4616 http://www.cnb.csic.es/content/research/macromolecular/mvraaij/index.php?l=1
On 5 Apr 2011, at 15:24, Van Den Berg, Bert wrote: > You may have a fairly long cell edge (or two if you are dealing with P3 or > P6), but you also seem to have high mosaicity (pic spot 1). Try the useful > strategies suggested here. It may also be worthwhile to shoot a few roomtemp > crystals to see if your cryo is at fault for your high mosaicity. > > Bert > > > On 4/5/11 9:10 AM, "dengzq1987" <[email protected]> wrote: > > hello Jürgen_Bosch, > > because i have collected the data,but can't index.in some direction,the spot > is separated .but the others are set close together(picture spot1 and spot > 2).so we think there is one long unit cell axes. > > 2011-04-05 > dengzq1987 > 发件人： Jürgen_Bosch > 发送时间： 2011-04-05 20:29:18 > 收件人： dengzq1987 > 抄送： [email protected] > 主题： Re: [ccp4bb] how to Collecting Data from Long Unit Cell Axes ? > > What do you consider long ? 200, 300 ? 600 A ? Before shooting try to run > strategy or xplan. Move the detector back to first reliably be able to > determine your cell. Then double your estimated mosaicity and see what > strategy suggests. If you don't get many overlaps (<5%) then try a closer > distance. Don't rotate 1degrees but take 1/2 of the mosaicity. Obviously you > want to make good use of the detector area so adjust the edges to where your > crystal really diffracts. And if that resolution leads to too many overlaps > then limit your resolution and get first a good datasets home. You then can > play with 2theta for a higher resolution dataset. > Another obvious thing to do and you don't mention what reduction program you > use is to let XDS sort your problem out. Unless you collected to high > resolution without being cautious XDS could help. If not, well then you had > your experience and now should know better. > SSRL has options to collect 450 A cells to 3A without much hassle. That was > my largest cell so far. > Jürgen > > ...................... > 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/ > > On Apr 5, 2011, at 1:05, dengzq1987 <[email protected]> wrote: > > > > hello all, > > does anyone have the experience of Collecting Data from Long Unit Cell Axes > ? I have a crystal that diffracts to about 4 A. in some direction the > spots overlap. we can't use the data to index .we think it is because that > there is a long unit cell axes. so is there any method to solve this > problem? > > > > best wishes. > > > > 2011-04-05 > > > dengzq1987 >
