Enhancement of Lysozyme Crystallization Using DNA as a Polymeric Additive
Bo Zhang,
Yao Wang,
Shiki Thi,
Vincent Toong,
Ping Luo,
Shilong Fan,
Lijin Xu,
Zhongqiang Yang,
Jerry Y. Y. Heng
Affiliations
Bo Zhang
Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
Yao Wang
Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
Shiki Thi
Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
Vincent Toong
Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
Ping Luo
State Key Laboratory of Biomembrane, Center for Structural Biology School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
Shilong Fan
State Key Laboratory of Biomembrane, Center for Structural Biology School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
Lijin Xu
Department of Chemistry, Renmin University of China, Beijing 100872, China
Zhongqiang Yang
Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
Jerry Y. Y. Heng
Surfaces and Particle Engineering Laboratory (SPEL), Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
This study reports the first experimental evidence of using DNA as a polymeric additive to enhance protein crystallization. Using three kinds of DNA with different molecular weights—calf DNA, salmon DNA, and herring DNA—this study showed an improvement in the success rate of lysozyme crystallization, as compared to control experiments, especially at low lysozyme concentration. The improvement of crystallization is particularly significant in the presence of calf DNA with the highest molecular weight. Calf DNA also speeds up the induction time of lysozyme crystallization and increases the number of crystals per drop. We hypothesized the effect of DNA on protein crystallization may be due to the combination of excluded volume effect, change of water’s surface tension, and the water competition effect. This work confirms predications of the potential use of DNA as a polymeric additive to enhance protein crystallization, potentially applied to systems with limited protein available or difficult to crystallize.
