Crystallization of Lysozyme on Metal Surfaces Using a Monomode Microwave System

The effect of metal surfaces on the crystallization of lysozyme using the Metal-Assisted and Microwave-Accelerated Evaporative Crystallization (MA-MAEC) technique and a monomode microwave system is described. Our microwave system (is called the iCrystal system hereafter for brevity) is comprised of a 100 W variable power monomode microwave source, a monomode cavity, fiber optic temperature probes and digital cameras. Crystallization of lysozyme (a model protein) was conducted using the iCrystal system on four different types of circular crystallization plates with 21-well sample capacity (i.e., crystallization plates): (ⅰ) blank: a continuous surface without a metal, (ⅱ) silver nanoparticle films (SNFs): a discontinuous metal film, (ⅲ) iron nano-columns: a semi-continuous metal film, and (ⅳ) indium tin oxide (ITO): a continuous metal film. Lysozyme crystals grown on all crystallization plates were characterized by X-ray crystallography and found to be X-ray diffraction quality. The use of iron nano-columns afforded for the growth of largest number of lysozyme crystals with a narrow size distribution. ITO-modified crystallization plates were deemed to be best of all the crystallization plates based on the observations that lysozyme crystals were grown at the shortest time (370 ± 36 minutes) with a narrow size distribution up to 460 m in size.