Chapter 8 Advances in Microfluidic Membrane Protein Crystallization Techniques

Abstract

Publisher Summary The pursuit of crystallizing membrane proteins suffers from a variety of ailments, such as low protein expression yields, difficult purification of active protein species, and awkward fluid handling properties that are due to the protein's requirement to be solubilized in an amphiphile environment. Membrane protein crystallization poses a substantial challenge, the reason of which is that transmembrane proteins remain functional and folded only when a proper microenvironment is supplied that allows interaction with a high and a low dielectric medium with the proteins' aqueous and membraneous moieties, respectively. Microfluidic devices for protein crystallization have been designed to consume small amounts of protein, be inexpensive and amenable to use in high-throughput protein crystallization efforts. Although recent reports on membrane protein crystallizations in microfluidic devices are a relatively new addition to the arsenal of tools available to membrane protein crystallographers, they are promising. Consuming 5-100 times less sample volume as compared to traditional pipetting technologies, they provide unique crystallization regimes for (1) free interface diffusion (FID), (2) gradients, and (3) microbatch experiments in plugs. This chapter reviews those microfluidic crystallization methodologies that have proven their utility for membrane protein crystallization. As the peculiar advantages and shortcomings of the individual systems become better understood, further integration and their specific significance for membrane proteins will aid in guiding the future development of these technologies.