High-pressure small-angle X-ray scattering cell for biological solutions and soft materials

Rai, D.K. Gillilan, R.E. Huang, Q.; Miller, R; Ting, E.; Lazarev, A.; Tate, M.W.; Gruner, S.M. 

Pressure is a fundamental thermodynamic parameter controlling the behavior of biological macromolecules. In many cases pressure alters molecular shape and therefore also the biological function. Small angle X-ray scattering (SAXS) is a widely used method to determine the shape and size of macromolecules, but typical sample cells for SAXS experiments are unsuitable for use at high pressures. 

HPSAXS Cell at CHESS

Novel high pressure BioSAXS cell.  (A) Internally water-cooled temperature control jacket; (B) Removable top pressure-seal assembly; (C) Stainless steel body; (D) Carbide through-rods; (E) Diamond seat assembly; (F) Sample in a removable plastic insert; (G) Diamond X-ray window. A high-pressure pump is used to pressurize fluid in the space between the diamond windows.

Rai and co-workers addressed this problem by developing a novel high-pressure SAXS cell that is suitable for routine use. By using single-crystal diamond windows in combination with high-energy X-rays, SAXS data can be obtained from biological samples at up to 4000-times atmospheric pressure (400 MPa) with temperatures ranging from 0 to 80C. This cell design prioritizes ease of sample loading, temperature control, mechanical stability and X-ray background minimization. In combination with a new EIGER 4M detector in vacuum, scattering can be routinely measured over a wide range of angles (a q range of 0.01 < q < 0.7 Å-1). This cell is a critical new tool for users studying pressure-induced changes to macromolecule shape and function at CHEXS, and has been deployed for users at beamline ID7A1 (HP-Bio/BioSAXS).

Importance

Pressure affects the fundamental activity and structure in biological assemblies. Pressures in the range encountered in the biosphere are known to have many effects on biomacromolecules, including alteration of protein denaturation, dynamics and kinetic constants of enzymes, ligand binding, membrane permeability, ion transduction, expression of genetic information, bacterial motility, viral infectivity, and molecular association and aggregation. Pressure is a valuable tool for understanding biophysical processes, but also is of great interest in the high-pressure food processing (HPP) and pharmaceutical industries. There is even a growing realization that a significant part of the planetary biomass lives under high pressure in the depths of the oceans and in the Earth’s crust. This realization is catalyzing interest in the biophysics of the large molecules of life as a function of pressure.

Need for CHEXS Experimental Capabilities

The NSF-funded HPBio beamlines at CHEXS are dedicated to addressing problems in biophysics at high pressure, and understanding the biological rules of “deep life” – those which govern organisms living under pressure. In service of a growing community of researchers working in the field of high-pressure biology, CHEXS is working to deliver powerful x-ray tools for structural biology in the high-pressure regime relevant for deep life. Combining these new sample cells with the bright x-ray beams at CHEXS facilitates these new kinds of experiments to be performed more quickly and easily than ever before, and with higher precision.

 

The pressure system controls and plumbing.
The BioSAXS pressure cell integrated into beamline ID7A1. This system is available to users on a peer-reviewed proposal basis, and supported for remote / mail-in use under our current remote access (Covid-19) restrictions. 

Funding

This work was based upon research conducted at the Center for High Energy X-ray Sciences (CHEXS), which is supported by the National Science Foundation under award DMR-1829070, and at the Macromolecular Diffraction at CHESS (MacCHESS) facility, which is supported by award 1-P30-GM124166-01A1 from the National Institute of General Medical Sciences, National Institutes of Health, and by New York State’s Empire State Development Corporation (NYSTAR). Sample cells were fabricated at the Cornell NanoScale Facility, an NNCI member supported by grant No. NNCI-1542081.

 

Reference

Durgesh K Rai, Richard E Gillilan, Qingqiu Huang, Robert Miller, Edmund Ting, Alexander Lazarev, MW Tate, and Sol M Gruner.  High-pressure small-angle X-ray scattering cell for biological solutions and soft materials.  J. Appl. Cryst. (2021) 54;  https://doi.org/10.1107/S1600576720014752