A comparison of gas stream cooling and plunge cooling of macromolecular crystals

Harrison, K.; Wu, Z.; Juers, D.H.

doi:10.1107/S1600576719010318

Figure 3
Plots of e₃ mosaicity versus resolution, d, for crystals of tetragonal thermolysin gas stream cooled and plunge cooled with different cryoprotective agents. (a) Comparison of gas stream cooled crystals [protocol (1), Section 2.2

] with an RT crystal. (b) Comparison of plunge cooled crystals [protocol (3), Section 2.2

] with an RT crystal. The upward shift relative to RT indicates greater strain or angular spread of domains, whereas slopes that are less negative or positive suggest a smaller domain size. The plots indicate that plunge cooling tends to produce a smaller domain size than gas stream cooling, as well as increased variation in unit-cell dimensions and/or domain orientations. Data are based on 2 × 50 0.2° frames roughly separated by 90°, with exposure times of 12–16 s per frame. Each plot is the average of the two 50-frame runs and within the particular resolution bin being plotted. Note that the smaller oscillation width (0.2°) than the other experiments (0.5°) reduces e₃, so the e₃ values here and in Table 2

are not comparable to e₃ values in other graphs and tables. Additionally, the relatively large beam divergence of our in-house X-ray source will mask small increases in crystal disorder (i.e. gas stream cooled xylose soaked crystals are likely to be more disordered than the RT crystal, although they have nearly identical parameters).

JOURNAL OF
APPLIED
CRYSTALLOGRAPHY

ISSN: 1600-5767

Volume 52| Part 5| October 2019| Pages 1222-1232

https://doi.org/10.1107/S1600576719010318

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