my experiences: C2 with a long axis parallel to the shortest crystal dimension, crystals were plates. Used prebent loops to fish the crystals. Personally I haven't tried to bend loops in mounted crystals as Frank does, but it sounds very useful. bar-shaped P321 crystals with hexagonal cross-sections, these naturally "fell" into loops in the "right" orientations. Too "right" usually, because you also don't want the long axis too parallel to the rotation axis and have a large blind cone compromising completeness, 10-20º from parallel is great, here a minikappa or the bendable loop mounts are very useful.
Mark J van Raaij Laboratorio M-4 Dpto de Estructura de Macromoleculas Centro Nacional de Biotecnologia - CSIC c/Darwin 3 E-28049 Madrid, Spain tel. (+34) 91 585 4616 http://www.cnb.csic.es/~mjvanraaij On 7 Mar 2012, at 08:44, Frank von Delft wrote: > Yes... quite. Thanks! > > (Beam, rotation axis... how can you expect me to keep all these new-fangled > inventions apart?!) > > > > On 07/03/2012 07:33, VAN RAAIJ , MARK JOHAN wrote: >> typo correction, you'll want the long axis parallel to the rotation >> axis, not to the beam. >> Mark >> >> Quoting Frank von Delft: >> >>> You probably have to tilt your crystal, so that the long axis is >>> parallel to the beam. We do this routinely: cut a plastic pipette >>> tip to have a sharp point, then push the loop where it attaches to >>> the pin, to bend the crystal itself. >>> >>> You have to identify from your diffraction whether the long axis is >>> pointing through the face or the edge of the loop. As it's P6, >>> chances are it's through the face, because long-axis P6 tends to >>> make flat hexagons which lie flush with the face. So you have to >>> bend so the face of the loop upwards. >>> >>> You'll have to practice this first, though, so put up an empty loop. >>> Top tips: >>> * Don't breathe! You'll blow the cryostream away. >>> * Bend the loop towards (rather than away from) the rim edge of >>> the pin to which it's glued. >>> * Don't breathe! >>> * Practise practise practise. >>> >>> >>> Another thing: most in-house sources allow you to reduce divergence >>> of the beam. You lose intensity, but no matter, just expose longer. >>> That also improves overlap. >>> >>> Cheers >>> phx >>> >>> >>> >>> On 07/03/2012 04:56, Dipankar Manna wrote: >>>> Dear Crystallographers, >>>> >>>> I am working on a protein having SG P6, the cell parameters are a= >>>> 79, b= 79, c= 325. The crystals are forming in big size and with >>>> very good shape. It also diffracting very well in Home source >>>> facility both in terms of resolution and intensity. But the only >>>> problem is the number of overlaps. Its showing much more than the >>>> good spots. As a result the completeness is showing maximum up to >>>> 65% even after collecting 180 degrees. I am unable to get a >>>> complete data. I tried with reducing the oscillation angel to 0.3 >>>> degree/0.5 degree but it did not improve that much. Please give me >>>> some suggestions. >>>> >>>> Regards, >>>> >>>> Dipankar >>>> >>>> /Dipankar Manna/ >>>> >>>> */Aurigene Discovery Technologies Limited,/* >>>> >>>> /#39-40 KIADB Industrial Area, Electronic City, Phase II,/ >>>> >>>> /Hosur Road, Bangalore- 560 100, India/ >>>> >>>> /Cell: +91-9538631469 // | Office Ph : +91 80-66204422 (Extn: 398) >>>> | Email ID: dipanka...@aurigene.com/ >>>> >>>> >>>> ------------------------------------------------------------------------ >>>> >>>> This e-mail and any files transmitted with it are for the sole use >>>> of the intended recipient(s) and may contain confidential and >>>> privileged information.If you are not the intended recipient, >>>> please contact the sender by reply e-mail and destroy all copies of >>>> the original message.Any unauthorized review, use, disclosure, >>>> dissemination, forwarding,printing or copying of this email or any >>>> action taken in reliance on this e-mail is strictly prohibited and >>>> may be unlawful. >>>> >>>> Visit us at http://www.aurigene.com >> >> >> Mark J van Raaij >> Laboratorio M-4 >> Dpto de Estructura de Macromoléculas >> Centro Nacional de Biotecnología - CSIC >> c/Darwin 3, Campus Cantoblanco >> 28049 Madrid >> tel. 91 585 4616 >> email: mjvanra...@cnb.csic.es >>
