Ionel Popa

Assistant Professor
 (414) 229-5086
 KEN 3180



Ionel Popa’s research focuses on developing and implementing new techniques to study the mechano-chemistry of proteins. At the nanoscopic level force is a ubiquitous perturbation and many proteins have evolved to respond to mechanical stimuli. These proteins are generally segregated in multiple domains and play key roles in processes such as cellular mechano-transduction and tissue elasticity. The lab is using a new single molecule force spectroscopy technique based on magnetic tweezers to study the response of proteins to mechanical perturbations. This technique allows tethering of a single protein for more than a day and at forces similar to those encountered in vivo. Using this technique we aim to produce a detailed synthesis of the chemical and physical mechanisms that regulate proteins operating under mechanical force.

Biographical Sketch

Ionel Popa received his B.Sc. degree in Chemical Engineering from Gh. Asachi Technical University in 2005 and his Ph.D. in Physical and Analytical Chemistry from University of Geneva in 2010, under the direction of Prof. Michal Borkovec. He then joined the group of Julio M. Fernandez at Columbia University to study protein biophysics, where he held the positions of Postdoctoral Fellow and Associate Research Scientist. Since fall 2015, he joined the University of Wisconsin-Milwaukee, where he currently holds the rank of Assistant Professor.

Selected Publications

Popa, Ionel, and Gutzman, Jennifer H. “The extracellular matrix–myosin pathway in mechanotransduction: from molecule to tissue.” Emerging Topics in Life Sciences 2.5 (2018): 727-737.
Popa, Ionel, and Berkovich, Ronen. “Mechanobiology: Protein refolding under force.” Emerging Topics in Life Sciences 2.5 (2018): 687-699.
Khoury, Luai R., Nowitzke, Joel, Dahal, Narayan, Shmilovich, Kirill, Eis, Annie, and Popa, Ionel. “Force-Clamp Rheometry for Characterizing Protein-based Hydrogels.” Journal of Visualized Experiments 138. (2018): e58280.
Khoury, Luai R., Nowitzke, Joel, Shmilovich, Kirill, and Popa, Ionel. “Study of Biomechanical Properties of Protein-Based Hydrogels Using Force-Clamp Rheometry.” Macromolecules/ACS 51.4 (2018): 1441 – 1452.
Shmilovich, Kirill, and Popa, Ionel. “Modeling protein-based hydrogels under force.” Physical Review Letters 121. (2018): 168101.
Valle-Orero, Jessica, Tapia-Rojo, Rafael, Eckels, Edward C., Rivas-Pardo, Jaime A., Popa, Ionel, and Fernández, Julio M. “Proteins Breaking Bad: A Free Energy Perspective.” The Journal of Physical Chemistry Letters 8. (2017): 3642-3647.
Valle-Orero, Jessica, Rivas-Pardo, Jaime A., and Popa, Ionel. “Multidomain proteins under force.” Nanotechnology 28.17 (2017): 174003.
Popa, Ionel, Rivas-Pardo, J A., Eckels, E C., Echelman, D J., Badilla, C L., Valle-Orero, J, and Fernández, J M. “A HaloTag Anchored Ruler for Week-Long Studies of Protein Dynamics.” Journal of the American Chemical Society 138.33 (2016): 10546-53.
Rivas-Pardo, J A., Eckels, E C., Popa, Ionel, Kosuri, P, Linke, W A., and Fernández, J M. “Work Done by Titin Protein Folding Assists Muscle Contraction.” Cell Reports 14.6 (2016): 1339-47.
Chen, H, Yuan, G, Winardhi, R S., Yao, M, Popa, Ionel, Fernandez, J M., and Yan, J. “Dynamics of equilibrium folding and unfolding transitions of titin immunoglobulin domain under constant forces.” Journal of the American Chemical Society 137.10 (2015): 3540-6.
Saqlain, F, Popa, Ionel, Fernández, J M., and Alegre-Cebollada, J. “A novel strategy for utilizing voice coil servoactuators in tensile tests of low volume protein hydrogels.” Macromolecular Materials and Engineering 300.3 (2015): 369-376.
Popa, Ionel, Berkovich, R, Alegre-Cebollada, J, Badilla, C L., Rivas-Pardo, J A., Taniguchi, Y, Kawakami, M, and Fernandez, J M. “Nanomechanics of HaloTag tethers.” Journal of the American Chemical Society 135.34 (2013): 12762-71.
Popa, Ionel, Kosuri, P, Alegre-Cebollada, J, Garcia-Manyes, S, and Fernandez, J M. “Force dependency of biochemical reactions measured by single-molecule force-clamp spectroscopy.” Nature Protocols 8.7 (2013): 1261-76.
Berkovich, R, Hermans, R I., Popa, Ionel, Stirnemann, G, Garcia-Manyes, S, Berne, B J., and Fernandez, J M. “Rate limit of protein elastic response is tether dependent.” Proceedings of the National Academy of Sciences of the United States of America 109.36 (2012): 14416-21.
Popa, Ionel, Fernández, J M., and Garcia-Manyes, S. “Direct quantification of the attempt frequency determining the mechanical unfolding of ubiquitin protein.” The Journal of Biological Chemistry 286.36 (2011): 31072-9.
Popa, Ionel, Sinha, P, Finessi, M, Maroni, P, Papastavrou, G, and Borkovec, M. “Importance of charge regulation in attractive double-layer forces between dissimilar surfaces.” Physical Review Letters 104.22 (2010): 228301.
Popa, Ionel, Gillies, G, Papastavrou, G, and Borkovec, M. “Attractive and repulsive electrostatic forces between positively charged latex particles in the presence of anionic linear polyelectrolytes.” The Journal of Physical Chemistry. B 114.9 (2010): 3170-7.
Popa, Ionel, Gillies, Graeme, Papastavrou, Georg, and Borkovec, Michal. “Attractive electrostatic forces between identical colloidal particles induced by adsorbed polyelectrolytes.” The Journal of Physical Chemistry B 113.25 (2009): 8458–8461.