my protein belong to glycosyltransferase got 1mm size of crystal the condition was 0.9M (NH4)2SO4 0.1M Bis-Tris 5.5 1-4% PEG400, but it diffract at low resolution 30A and 10A i used 30% glycerol as cropro. i thought low diffraction due to water so am asking what the proper method to do dehydration ? by increase pricipitant concentration after getting crystal coz i use PEG, or just i could use glycerol only with 10%, in reservoir? thanks in advance
Likely after dehydration the cristallinity of your material is lower because water is essential to stabilze the crystals.
Even if the crystal structure of your material is stable without water, it is sure that with the dehydration you increase the disorder and, consequently, you have the decrease of the diffracted intensities. What you can do is to try to make the dehydration as slow as possible in order to minimize such disorder...
2.- besium acetateOf course. Crystal structures of anhydrous or hydrated are not the same. When the water is lost at a particular temperature, the hydrated crystal structure is destroyed, and an amorphous disordered material appears (glass state).
Consult this two references:
1- Anhydrous Lithium Acetate Polymorphs and Its Hydrates:Three-Dimensional Coordination Polymers. F. J. Martínez Casado;Ramos Riesco; M. I. Redondo;D. Choquesillo-Lazarte; S. Lopez-Andres; and J. A. Rodríguez Cheda. Cryst.
Growth Des. 2011, 11, 1021–1032
it is said (sic): ......In this sense, vitreous lithium acetate can be obtained by
cooling the melt fast, and also by vacuum dehydration of LiC2 dihydrate, even at a rather low temperature (330 K), yielding amorphous lithium acetate. This latter rather unusual method has been also reported for magnesium acetate.(Ref. 59)
2.- Ref (59) of the previous article: Onodera, N.; Suga, H.; Seki, S. Bull. Chem. Soc. Jpn. 1968, 41(9), 2222
In detail I think it is not very clear why in some cases dehydration causes an improvement of crystal order whereas in most cases the opposite occurs. Some research has to be done in this direction to improve the situation of successful crystal transformation.
https://www.researchgate.net/post/Would_anyone_have_a_clue_as_to_the_origin_of_unexpected_spots_in_the_real_time_2D_XRR_signal_from_thin_film_samples_on_substrates_Yuneda_Spots
https://www.researchgate.net/post/What_is_the_best_way_to_interpret_REAL_TIME_3D_X_Y_o-2TH_o_ph_ch_reciprocal_space_relative_intensity_data_from_HRXRD_rocking_curve_analyses
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