Recent Advances in the Understanding of the Influence of Electric and Magnetic Fields on Protein Crystal Growth

Abstract

In this contribution we use nonconventional methods that help to increase the success rate of a protein crystal growth, and consequently of structural projects using Xray diffraction techniques. In order to achieve this purpose, this contribution presents new approaches involving more sophisticated techniques of protein crystallization, not just for growing protein crystals of different sizes by using electric fields, but also for controlling crystal size and orientation. This latter was possible through the use of magnetic fields that allow to obtain protein crystals suitable for both high-resolution X-ray and neutron diffraction crystallography where big crystals are required. This contribution discusses some pros, cons and realities of the role of electromagnetic fields in protein crystallization research, and their effect on protein crystal contacts. Additionally, we discuss the importance of room and low temperatures during data collection. Finally, we also discuss the effect of applying a rather strong magnetic field of 16.5 T, for shorts and long periods of time, on protein crystal growth, and on the 3D structure of two model proteins.

A Graphene-Based Microfluidic Platform for Electrocrystallization and In Situ X-ray Diffraction

“…These results agree with previous literature reports where a higher signal-to-noise [7] was observed for crystals grown in an electric field. It is important to note that this is the first report where direct, in situ measurements of the X-ray diffraction quality could be obtained on protein crystals grown via electrocrystallization, without the need for handling of fragile capillaries [16] or the use of hard X-rays to limit absorption from the crystallization cell [14].…”

“…Electrocrystallization platforms have been reported for a variety of crystallization schemes, including batch [6][7][8][9][10][11][14][15][16][17][18][19][20], vapor diffusion [5,[13][14][15][16], and counter-diffusion [21], taking advantage of both internal [6,7,[12][13][14][19][20][21][22] and external electric fields [5,[8][9][10]15,18,23]. These strategies have also explored the effects of constant (DC) [5][6][7][13][14][15][16][17][20][21][22] and alternating (AC) electric fields [8][9][10]...…”

“…These strategies have also explored the effects of constant (DC) [5][6][7][13][14][15][16][17][20][21][22] and alternating (AC) electric fields [8][9][10][11][12][16][17][18]. However, the benefits observed for the various electrode arrangements and crystallization setups reported to date have been limited by the need to manually harvest crystals for subsequent diffraction analysis.…”

Recent Insights into the Crystallization Process; Protein Crystal Nucleation and Growth Peculiarities; Processes in the Presence of Electric Fields

“…A significant increase in both crystal size homogeneity and ratio of magnetically orientated crystals as compared with the controls is reported. Most recently, some sophisticated techniques for protein crystallization using dc (in the range of 2-6 µA) and ac (in the range of 2-8 Hz) have enabled control over crystal nucleation, size and orientation (the latter governed by a rather strong magnetic field of 16.5 T) [16]. These techniques allow for obtaining large and suitable crystals not only for high-resolution synchrotron X-ray, but also for neutron-diffraction crystallography.…”

“…Pioneered by Aubry's group [4,5] some 20 years ago, protein crystallization under EF attracts an increasing attention, becoming a mature scientific branch today. Major contributions in this research field have been made by the teams of Moreno [6][7][8][9][10][11][12][13][14][15][16][17], Koizumi [18][19][20][21][22][23][24][25][26][27][28][29], Veesler [30][31][32][33], etc. (the list is not exhaustive).…”