Dedicated to state-of-the-art time-resolved research in biological and physical sciences.


BioCARS micro-spectrophotometer for on-line and off-line recording of optical absorption spectra of crystals, to aid X-ray diffraction studies.

Laser Lab

BioCARS ps laser system: Spectra Physics, Ti:Sapphire Spitfire Pro 5 (780nm, 2ps, 1kHz, 5mJ/pulse) and TOPAS OP

14-ID Beamline

BioCARS 14 ID beamline provides necessary infrastructure for conducting state-of-the-art time-resolved X-ray scattering studies with 100ps time resolution, both in biology and in physical sciences.

Laue X-ray Diffraction Pattern

Laue diffraction pattern collected at 14 ID from a Scapharca Inequivalvis tetrameric hemoglobin crystal, as part of 100ps time-resolved studies.

Update on Status at BioCARS, August 20, 2020

Dear BioCARS Users,
2020-3 cycle will start on October 1 and APS plans to move to Limited Operations Plus phase.

In this phase, only mail-in/remote access experiments are feasible. Onsite access remains prohibited for external users at APS. For latest announcements, please check the APS home page at or the User Info page at

Please contact BioCARS staff scientists contacts to discuss the compatibility of your experiments in this operations phase.

Our Mission

BioCARS is a national user facility for synchrotron-based, dynamic studies in structural biology, located at Sector 14 of the Advanced Photon Source, at Argonne National Laboratory. BioCARS is an integral part of the multi-disciplinary Center for Advanced Radiation Sources (CARS) run by the University of Chicago.

Structural biology at BioCARS is supported by the National Institute of General Medical Sciences of the National Institutes of Health under grant number P41 GM118217.

The mission of BioCARS is to provide state-of-the-art X-ray facility, scientific and technical expertise and support to enable users to study the dynamic properties of biological macromolecules by X-ray scattering techniques: time-resolved diffraction and solution scattering (SAXS/WAXS). In hybrid mode of the APS storage ring, BioCARS 14-ID beamline provides high polychromatic flux, with a number of photons per 100ps pulse approaching that of free electron lasers (such as the LCLS). Short X-ray pulses are synchronized with ps or ns laser pulses for conducting pump-probe time-resolved experiments. Laser pulses are used to initiate reactions in naturally photo-sensitive proteins or in other proteins that can be used with a suitable caged compound, and to initiate temperature or pH jumps. We are currently developing methods and technology for serial Laue micro-crystallography in order to facilitate studies of irreversible reactions while minimizing sample consumption. Another exciting field we are focusing on is the development of electric-field jump as a method for reaction initiation and studies of protein dynamics. The overall goal of time-resolved experiments our users conduct is to understand basic biological processes in structural and dynamics terms, on time scales from 100 picoseconds to seconds.

BioCARS operates two Experimental Stations, embedded in a Biosafety Level 3 (BSL-3) Facility. This BSL-3 synchrotron-based capability is unique in the United States and permits safe studies of biohazardous materials such as pathogenic human viruses.
*As of February 6, 2017, BioCARS facility is decommissioned as a BSL-3 laboratory. BioCARS is now approved for research up to the BSL-2 level.

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Recent Publications

Kim, H., Kim, J. G., Muniyappan, S., Kim, T. W., Lee, S. J., and Ihee, H. (2020)
Effect of Occluded Ligand Migration on the Kinetics and Structural Dynamics of Homodimeric Hemoglobin.
J. Phys. Chem. B 124, 1550–1556.

Thompson, M. C., Barad, B. A., Wolff, A. M., Cho, H. S., Schotte, F., Schwarz, D. M. C., Anfinrud, P., and Fraser, J. S. (2019)
Temperature-jump solution X-ray scattering reveals distinct motions in a dynamic enzyme.
Nat. Chem. 11, 1058–1066.

Rimmerman, D., Leshchev, D., Hsu, D. J., Hong, J., Abraham, B., Henning, R., Kosheleva, I., and Chen, L. X. (2019)
Revealing Fast Structural Dynamics in pH-Responsive Peptides with Time-Resolved X-ray Scattering.
J. Phys. Chem. B 123, 2016–2021.

Martin-Garcia, J. M., Zhu, L., Mendez, D., Lee, M.-Y., Chun, E., Li, C., Hu, H., Subramanian, G., Kissick, D., Ogata, C., Henning, R., Ishchenko, A., Dobson, Z., Zhang, S., Weierstall, U., Spence, J. C. H., Fromme, P., Zatsepin, N. A., Fischetti, R. F., Cherezov, V., and Liu, W. (2019)
High-viscosity injector-based pink-beam serial crystallography of microcrystals at a synchrotron radiation source.
IUCrJ 6, 412–425.

Hsu, D. J., Leshchev, D., Rimmerman, D., Hong, J., Kelley, M. S., Kosheleva, I., Zhang, X., and Chen, L. X. (2019)
X-ray snapshots reveal conformational influence on active site ligation during metalloprotein folding.
Chem. Sci. 10, 9788–9800.

Berntsson, O., Rodriguez, R., Henry, L., Panman, M. R., Hughes, A. J., Einholz, C., Weber, S., Ihalainen, J. A., Henning, R., Kosheleva, I., Schleicher, E., and Westenhoff, S. (2019)
Photoactivation of Drosophila melanogaster cryptochrome through sequential conformational transitions.
Science Advances 5, eaaw1531.

Latest News and Highlights

Temperature-jump solution X-ray scattering reveals distinct motions in a dynamic enzyme

September 16, 2019

Correlated motions of proteins are critical to function, but these features are difficult to resolve using traditional structure determination techniques. Time-resolved X-ray methods hold promise for addressing this challenge, but have relied on the exploitation of exotic protein photoactivity, and are therefore not generalizable. Temperature jumps, through thermal excitation of the solvent, have been utilized to study protein dynamics using spectroscopic techniques, but their implementation in X-ray scattering experiments has been limited. Here, we perform temperature-jump small- and wide-angle X-ray scattering measurements on a dynamic enzyme, cyclophilin A, demonstrating that these experiments are able to capture functional intramolecular protein dynamics on the microsecond timescale.

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High-viscosity injector-based pink-beam serial crystallography of microcrystals at a synchrotron radiation source

May 1, 2019

Since the first successful serial crystallography (SX) experiment at a synchrotron radiation source, the popularity of this approach has continued to grow showing that third-generation synchrotrons can be viable alternatives to scarce X-ray free-electron laser sources.

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Science Careers in Search of Women Conference, Tour of BioCARS

April 4, 2019

As in previous years, BioCARS participated again in the ANL-hosted annual Science Careers in Search of Women Conference this year (Click here for more).

Crystal-on-crystal chips for in situ serial diffraction at room temperature

June 20, 2018

Recent developments in serial crystallography at X-ray free electron lasers (XFELs) and synchrotrons have been driven by two scientific goals in structural biology – first, static structure determination from nano or microcrystals of membrane proteins and large complexes that are difficult for conventional cryocrystallography, and second, direct observations of transient structural species in biochemical reactions at near atomic resolution.

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New BioCARS Director, Prof. Rama Ranganathan

December 2017

Distinguished biophysicist Rama Ranganathan joined University of Chicago as a professor in the Department of Biochemistry and Molecular Biology and Institute for Molecular Engineering. He is the new Director of BioCARS facility and will also lead the new Center for Physics of Evolving Systems at the University of Chicago.

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Effect of Occluded Ligand Migration on the Kinetics and Structural Dynamics of Homodimeric Hemoglobin

February 6, 2020

Small molecules such as molecular oxygen, nitric oxide, and carbon monoxide play important roles in life, and many proteins require the transport of small molecules to and from the bulk solvent for their function. Ligand migration within a protein molecule is expected to be closely related to the overall structural changes of the protein, but the detailed and quantitative connection remains elusive. For example, despite numerous studies, how occluded ligand migration affects the kinetics and structural dynamics of the R–T transition remains unclear. To shed light on this issue, we chose homodimeric hemoglobin (HbI) with the I114F mutation (I114F), which is known to interfere with ligand migration between the primary and secondary docking sites, and studied its kinetics and structural dynamics using time-resolved X-ray solution scattering. The kinetic analysis shows that I114F has three structurally distinct intermediates (I1, I2, and I3) as in the wild type (WT), but its geminate CO recombination occurs directly from I1 without the path via I2 observed in WT.

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