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Figure 3
Structures of proteinase K determined by spray-freezing and traditional plunge-freezing methods. The apo-form structure of proteinase K crystals at 2.2 Å resolution prepared by standard blotting and plunge-freezing methods is superimposed with the 2Fo − Fc map at a 1.5σ level viewing the empty active site in chain A (a) and chain B (b) of the asymmetric unit. The active site is in good agreement with that of a 2.5 Å resolution structure determined exclusively from spray-frozen proteinase K crystals (c, d). (e) and (f) show the same views as (c) and (d), respectively, with the σ level of the 2Fo − Fc map reduced to 1.0.

IUCrJ
Volume 13| Part 4| July 2026|
ISSN: 2052-2525
https://doi.org/10.1107/S2052252526005129