Flash-freezing causes a stress-induced modulation in a crystal structure of soybean lipoxygenase l3.

A dynamic conformational flexibility of a protein might be a source of non-covalent structural heterogeneity, causing diminished diffracting ability of crystals and disorder in a crystal structure of soybean lipoxygenase L3. Room-temperature data, space group C2, correspond to a structure with large channels lined mostly or in part by disordered fragments of the molecule or flexible loops with an increased thermal vibration. A rapid change in temperature of approximately 200 K creates a wave of a stress-induced modulation that propagates in the crystal changing its reciprocal space into a three-dimensional quilt-like mixture of C and P intertwined lattices. Low-temperature data indicate a transformation from the dynamic to static disorder, leading to a primitive unit cell with 10% reduced volume. The molecules, formerly related by a twofold axis are rotated by approximately 7 degrees and are shifted along the diagonal to be approximately 4 A, closer together. During a routine data collection for the flash-frozen crystals of similar properties such phenomena could easily go unnoticed leading to biased results because of such effects and possibly improper indexing of the data.