Introduction to protein crystallization

Abstract

Protein crystallization was discovered by chance about 150 years ago and was developed in the late 19th century as a powerful purification tool and as a demonstration of chemical purity. The crystallization of proteins, nucleic acids and large biological complexes, such as viruses, depends on the creation of a solution that is supersaturated in the macromolecule but exhibits conditions that do not significantly perturb its natural state. Supersaturation is produced through the addition of mild precipitating agents such as neutral salts or polymers, and by the manipulation of various parameters that include temperature, ionic strength and pH. Also important in the crystallization process are factors that can affect the structural state of the macromolecule, such as metal ions, inhibitors, cofactors or other conventional small molecules. A variety of approaches have been developed that combine the spectrum of factors that effect and promote crystallization, and among the most widely used are vapor diffusion, dialysis, batch and liquid-liquid diffusion. Successes in macromolecular crystallization have multiplied rapidly in recent years owing to the advent of practical, easy-to-use screening kits and the application of laboratory robotics. A brief review will be given here of the most popular methods, some guiding principles and an overview of current technologies.

An Overview of the Top Ten Detergents Used for Membrane Protein Crystallization

“…To aggravate that, polyethelene glycol is a typical by-product, and additionally peroxides were reported to be present in the detergent preparations as the result of aging [65]. This explains the significant difference between the number of cases, where Triton X-100 was used for extraction/purification (1.8%) and for crystallization (0.3%), where typically homogeneity and purity play a crucial role in crystallogenesis [66].…”

“…It has a steroid-like saposin structure (Figure 12). significant difference between the number of cases, where Triton X-100 was used for extraction/purification (1.8%) and for crystallization (0.3%), where typically homogeneity and purity play a crucial role in crystallogenesis [66].…”

Crystallization, solubility and thermodynamics of the highly thermostable glucose isomerase from Streptomyces sp. strain

“…Macromolecular crystallization, which includes the crystallization of proteins, nucleic acids, and larger macromolecular assemblies such as viruses and ribosomes, is based on a rather diverse set of principles, experiments and ideas (McPherson 2004;Srimahaprom and Flood 2013). It is very often the most difficult and time-consuming step in the determination of a protein's atomic structure.…”

A Double Emulsion-Based, Plastic-Glass Hybrid Microfluidic Platform for Protein Crystallization

“…Alternatively, microfluidic techniques emerge with attractive features in manipulating small volumes (picoliter to nanoliter) of reagents by a relatively simple and economic way [17,18] Miniaturization through microfluidics can be used to crystallize proteins and provide unique experimental conditions that are either difficult or impossible with macroscopic tools. Different kinds of microfluidic systems, including valve-based systems [19,20], droplets-based systems [21][22][23] and microwell-based systems [24][25][26][27][28], have been developed to implement the conventional protein crystallization methods of vapor diffusion, microbatch, dialysis and free interface diffusion [1,16].…”

“…The atomic structure of protein molecules is important both for understanding the architectures and functions of living matter and for providing essential knowledge to the pharmaceutical industry, such as new drug discovery and medical therapy [1][2][3]. There have been several techniques developed for determining the three-dimensional protein structures in laboratories, including X-ray crystallography [4][5][6][7], nuclear magnetic resonance spectroscopy (NMR) [8] and cryo-electron microscopy [9,10].…”