People
Much of what is known about protein dynamics has been studied using bulk biochemical techniques and chemical denaturants. By contrast, we study proteins at the single molecule level and use mechanical forces to denature proteins. Force is a ubiquitous denaturant in biology. Our results are opening new vistas into protein function and challenging some widely accepted views of protein dynamics.
Recent courses taught at Columbia University:
- Frontiers of Science, Science C1000 (Spring 2006)
- The Biology and Physics of Single Molecules, Biology Biology W4070 (Fall 2006)
- Cellular Physiology of Disease, Biology W3008 (Spring 2007)
I obtained my Ph.D. degree in Physical Chemistry from the University of Granada under the supervision of Dr. Jose M. Sanchez-Ruiz and Dr. Beatriz Ibarra-Molero. My thesis work focused mainly in an attempt to define the role of surface charge interactions in protein stability as well as the study of the evolutive information obtained from sequence alignments and its consequences in protein folding, structure and stability. My interest now is focused in the study of the protein folding as well as the mechanical stability using Single Molecule Force Spectroscopy. The techniques developed in Dr. Fernandez's Lab have become a powerful tool for the study of protein folding/unfolding processes under a stretching force in a new manner that reveals features of proteins non accessible with bulk techniques. I am interested in the use of the Force-clamp techniques to understand how a protein finds the way to fold into a native state and what are the more important aspects involved.
Jian Liang joined the Fernandez lab in November 2007, as a postdoctoral research scientist in the Department of Biological Sciences at Columbia University. Jian was born in Guangzhou, China. He obtained his B. S. degree in chemistry and M. S. degree in physical chemistry both from the College of Chemistry and Molecular Engineering at Peking University in the years of 1999 and 2002, respectively. After that, he moved to the U.S. and pursued his Ph.D. degree in the Department of Chemistry at Princeton University. In October 2007, Jian completed his thesis defense and then started his new life in New York City. During his studies in China and in the U.S., Jian has been interested in using various techniques to probe different properties at surfaces and interfaces, especially in the field of soft molecular materials, molecular manipulation, chemical/mechanical/electrical properties at the molecular or nanoscale level, scanning probe microscopy and the properties of self-assembled monolayers. Currently, Jian is expanding his area of interest towards biological systems, using single-molecule force spectroscopy to study the physical, chemical and mechanical properties of proteins.
In 2003, I graduated in Biochemistry from the Complutense University of Madrid, Spain (1st National Award). I obtained my PhD degree after five years of research at the Department of Biochemistry and Molecular Biology I (Complutense University). My Thesis work, which was supervised by Drs. Á. Martínez del Pozo and J. G. Gavilanes, dealt with the study of the mechanism of pore formation by a family of eukaryotic pore-forming toxins, the actinoporins from sea anemones. We employed a variety of biochemical and biophysical approximations (site-directed mutagenesis, infrared spectroscopy, isothermal titration calorimetry, circular dichroism, fluorescence spectroscopy…) to gain insight into the way actinoporins interact with lipid membranes and the subsequent conformational changes they experience.
In May 2008 I joined Prof. Julio Fernandez lab with the aim of learning the single-molecule force spectroscopy techniques by atomic force microscopy. These techniques have provided the means to study the influence of force in the reduction of disulfide bonds, both by chemicals and enzymes. My current research projects are focused on expanding those experiments to other chemical bonds. Hopefully, the results will increase our knowledge on the influence of force in chemical reactions.
I graduated in Chemistry (Major: Physical Chemistry) from the University of Barcelona, Catalonia, in 2000 (extraordinary award in graduation) and in 2001 I finished my MS in Analytical Chemistry. In 2005 I obtained my PhD degree from the Department of Physical Chemistry (University of Barcelona) in the group of Nanobioscience under the supervision of Prof. Fausto Sanz. My PhD was mainly focused on the understanding of the nanomechanical properties of well-defined molecular systems through Force Spectroscopy with AFM. More precisely, I explored the different regimes of the force curves in order to try to understand the mechanical response of surfaces at the nanometric scale under the application of force. Concerning the hard contact region of the force plots (nN-µN scale), we were able to discern between different materials ranging from ionic (1) to covalent (2), especially focusing on the elastic regime and also on the onset of plastic deformation (nanoindentation) (3). Regarding the 'soft' contact region (nN range), I was concerned about the study of the mechanical response of lipid bilayers, and especially the role that ionic strength (4), temperature (5) and phospholipid chemical structure play upon membrane stability at the nanometer scale. The adhesion force and the jump-to-contact force (pN) provide an insight into chemical interactions that arise between a chemically functionalized tip and the target surface (6). From September 2005 I hold a postdoctoral research position in the laboratory of Prof. Julio Fernandez. My current research interests aim to extend the Force Spectroscopy applications to the field of unfolding single proteins upon the application of force, i.e., in the pulling regime of the force plots. In particular, I am interested in the measurement of single-bond rupture and also in the understanding of the unfolding and folding pathways that a protein undergoes under the application of constant force, which can be experimentally achieved by using the so-called force-clamp spectroscopy mode. References
Pallav Kosuri is a Fulbright Scholar and a Ph.D. candidate at the department of Biochemistry and Molecular Biophysics. He graduated with a Masters of Science degree in Physics from the Royal Institute of Technology in Stockholm, Sweden, and did his thesis research at the European Center for Nuclear Research (CERN) in Geneva, Switzerland. His current work at the Fernandez Lab employs extremely precise AFM technology to investigate physiologically important enzymatic systems on a single-molecule scale. The AFM also enables a direct measurement of force, a fact that he is exploring in the context of biological systems such as cell signaling and viral cell invasion.
In addition to research, he has spent part of his life as a photographer. Some photos can be seen on his website: http://www.pallav.se
Tzu-Ling Kuo is currently a graduate student in the Department of Physics at Columbia University. In September 2007, she joined Professor Fernandez's group to pursue her Ph.D. thesis research. Her current research project is to study the kinetics of protein unfolding and disulfide reduction using the force-clamp technique and fast AFM. Tzu-Ling received a Bachelor of Science degree in Physics from National Taiwan University. After finishing two years of coursework at Columbia, she received the degree of Master of Arts.
I am a Ph.D. student in the Applied Physics and Applied Mathematics Department of the School of Engineering and Applied Science. I am working in the Department of Biological Sciences with Professor Dr. Julio Fernández. My studies focus on using high speed force-clamp AFM techniques to study the mechanical properties of proteins. I am completing the writing of my PhD thesis and plan to graduate shortly.
Molecular Biologist and lab manager
I am in charge of the molecular biology section of the laboratory. I engineer most of the polyproteins that we use. We have a well established protocol for constructing polyproteins at the DNA level and then expressing them in bacteria. I use Talon columns and FPLC for protein purification. We struggle a bit with engineering AFM ready polyproteins. Not all of them give nice pulls. If so, I am the one that usually gets to re-engineer and/or re-express the proteins. I teach all the lab members how to do it and also I am happy to help other investigators by phone and email. I welcome inquiries.
