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 li poxygenase L3. Room-temperature data, space group C2, correspond to a structure with large channels lined mostly or in part by disordered fr agments of the molecule or flexible loops with an increased thermal vi bration. A rapid change in temperature of similar to 200 K creates a w ave of a stress-induced modulation that propagates in the crystal chan ging its reciprocal space into a three-dimensional quilt-like mixture of C and P intertwined lattices. Low-temperature data indicate a trans formation 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 similar to 7 degrees and are shifted alo ng the diagonal to be similar to 4 Angstrom closer together. During a routine data collection for the flash-frozen crystals of similar prope rties such phenomena could easily go unnoticed leading to biased resul ts because of such effects and possibly improper indexing of the data.