Direct Crystallization of Proteins from Impure Sources

In recent years, with the rapidly increasing demand for pure protein products in various fields (biomedicines, biochemical reagents, food industries, etc.), the need for low-cost, high-quality protein purification technology has become urgent. Under this background, the traditional purification technology, protein crystallization, comes back to people's attention. Protein crystallization has the ability to obtain high-quality protein products at a low cost. Nevertheless, protein crystallization itself is challenging; for a long time, the industrial purification of proteins often has used chromatography-based approaches. In the field of structural biology, the strong demand for protein crystals has led to the full development of protein crystallization technology. To date, these technologies may have the potential to provide solutions to achieve crystallization of proteins at the industrial scale. In this paper, we report our effort to screen the crystallization conditions of four sample proteins (lysozyme, hemoglobin, superoxide dismutase, and homoserine oxygen-acetyltransferase) from different impure sources (natural and recombined ones). It was confirmed that crystallization screening technology allows protein crystals to be obtained directly from impure protein sources, showing that, from the impure sources, the target protein can be purified directly by crystallization without prior purification using chromatographic processes. This work demonstrated that the new technologies developed in the field of protein crystallization methodologies can be well applied in solving problems in traditional purification technology.