Markey Center for Structural Biology

Krios Overview

Figures of Sputnik virus courtesy of Xinzheng Zhang.


Biological Sciences Electron Microscope Facility

The Hockmeyer Hall of Structural Biology is also the home for Purdue University's Biological Sciences Electron Microscopy Facility (BEMF), also known as the Science Women of Purdue Electron Microscopy Suite.  The facility is part of the Purdue EM Consortium and is available to Purdue-affiliated, as well as external users.  It was conceived to create the infrastructure for high-throughput structure determination of biological macromolecules and their assemblies by cryo transmission electron microscopy (cryo-TEM) and three-dimensional (3D) image reconstruction. The scientific program includes a variety of high-resolution studies of viruses and other larger macromolecular complexes, as well as tomographic visualization of virus-cell interactions. Researchers using the facility have published structures of human pathogens, such as poliovirus, dengue virus, and West Nile virus.

The Heart of the facility is its TITAN KRIOS, a state of the art transmission electron microscope capable of atomic resolution. It is one of the most advanced cryo transmission electron microscopes currently available. This instrument incorporates semi-robotic specimen handling and supports high-throughput acquisition rates.  It is specially suited for low dose imaging and tomography of macromolecular complexes in vitreous suspension or vitrified thin sections.  Relevant features include:

In addition to its built-in stability features, the microscope is housed in an electrically isolated room with computerized temperature and humidity control, and sits on a mechanically isolated concrete slab.  The column is optimized for use at 300kV, but can also be used at some lower acceleration voltages, down to 80kV.  The Krios was manufactured by FEI Company and belongs to the family of Titan microscopes.  When geared with beam and image correctors, these microscopes have resolved unprecedented atomic detail from inorganic materials.  In the biological applications, the Krios has resolved the structure of several viruses to a resolution comparable to that achievable by X-ray crystallography on similar structures. See, for example, the structure of Sputnik, determined by the Rossmann group to a resolution of 3.5 Å (Zhang et al. PNAS 109, 18431-18436, 2012).

Other equipment:

The BEMF also has a visualization room for remote control, observation of live data acquisition and preliminary processing. Digital acquisition software include:

The facility is staffed by:

Christopher J. Gilpin Ph.D., Interim Director

 Christopher Gilpin


Valorie Bowman, Senior Research Electron Microscopist.




Anyone interested in accessing the facility can contact the director for instructions on how to become a user.  Do notice that, in addition to BEMF, the EM Consortium also includes the Life Sciences Microscopy Facility (LSMF), administered by in the College of Agriculture, which provides access to other instrumentation in electron and light microscopy, and offers service and training towards Life Science research.

Our current hourly rates (USD/h) are the following:


Internal Users

External Users

Sample Preparation (by staff)



KRIOS (by staff)



KRIOS (by user)



CM200 (by staff)



CM200 (by user)



Operation of the instruments is limited to qualified users.  Training is charged at staff rates on the corresponding instrument.

Current reservation policies:



Reservation Horizon

14 days

14 days

Reservation time unit

1 h

24 h

Maximum time/day

8 h

24 h

Start time

Every hour 8:00 am to 3:00 am

8:00 am

Total Reservation Time/Horizon

48 h

72 h

Non-cryo usage


Extra warm-up day charged

Film usage

2 h of film pump-down charged

Last load must be done before 2:00 am


Qualified users can reserve time 14 days in advance.


Resources for BEMF users:


(Equipment instructions, methods and laboratory procedures)



1) BEMF is now a CTSI-designated core. Investigators from all CTSI partner institutuions are eligible to compete for CTSI Pilot Awards applicable to core services at our facility. Spring applications deadline is over. Next round in the Fall 2013.

2) Instrument scheduling is now done through CORAL.  If you have questions regarding how to get a Coral account, please contact the Coral administration at