Is there anything about a protein that I can learn from the fact that it crystallizes in 35% Pentaerythritol propoxylate. I am working on crystallizing a protein and keep hitting dead ends. I finally generated some small rod-like crystals using 35% Pentaerythritol propoxylate and 0.2M potassium acetate (no buffer). However, when placed in the x-ray beam they barely diffract (extremely low number of reflections and weak intensity). They do not appear to be salt. My working hypothesis is that these crystals are highly disordered.
I have fresh protein and will do the typically thing of screening buffers, salts, seeding. Just wondering if anyone has other suggestions.
Usually very thing rod like crystals are actually salt precipitate which forms when the salt in the protein solution mixes with the crystalising solution Have you done any test to make sure they are not salt crystal? UV microscopy should lit it up if they are protein crystals.
A similar question to your question was addressed in https://www.researchgate.net/post/Is_there_any_way_to_improve_the_diffraction_of_a_protein_crystal
Try some of the suggestions proposed in that post.
Wes Ozarowski already answered your questions. best will be to get another crystal forms which is more 3 dimensional. if you can not, try to optimize your crystal to increase the thickness as much as you can. after that, you can try micro focus beam line. its available at advanced photon source, chicago. beam line 24-ID-E and 24-ID-C and 23 ID. you can take advantage of a long crystal by shooting highly focused high intensity X-RAY at multiple spot on same crystals and margin the data together because such a high intensity beam is going to destroy your crystal quite fast. there are several strategy for collecting such data set. the beam line scientists should be able to help you with that.
Dhiraj
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