A first attempt investigation on crystallization screening and crystal quality of lysozyme under different simulated gravities in a large-gradient magnetic field

A magnetic field has been proved useful in protein crystallization in that it can help to improve the crystal quality, which is essential for high-resolution diffraction using crystallography. However, it is not widely utilized as a high-field magnet usually provides limited space which is usually too small for commercially available crystallization plates, so that the crystallization screening and optimization in such a magnet become a challenging task. Here we show that a specially designed flexible capillary array containing 96 conditions can be easily crimped into a small curl so that it can be accommodated into the bore of a large gradient superconducting magnet. Using the capillary array, we conducted a systematic investigation on the crystallization screening and crystal quality of lysozyme under different simulated gravities (μg, 1g, and 2g) in a large-gradient magnetic field and normal gravity outside the magnet. This is the first statistical study of the crystallization screening of protein in such a high-field magnet. The results showed that both the simulated gravity and the magnetic field affect the crystallization of lysozyme. The simulated microgravity can significantly improve the crystal quality, and the simulated hypergravity is helpful to increase the chance for obtaining crystallization conditions. Moreover, the method exhibits more potential features, such as the capability of in situ diffraction and the applicability for space experiments.