Lois Pollack
Associate Professor

Lois Pollack

Phone

607-255-8695

Address

College of Engineering School of A&EP
254 Clark Hall
Cornell University
Ithaca, NY 14853-2703

Email

Web Sites

Lab Web Site
Department Profile

Background

B.A. 1983 (Brandeis);
Ph.D. 1989 (Massachusetts Institute of Technology)

Research Description

My group is studying both self-assembly/folding of macromolecules and conformational changes associated with biological function.  We develop and use new tools to trigger and monitor shape changes to access novel information about these processes. 

Conformational changes can be triggered by modifying the solvent around a macromolecule.  For example, protein folding can occur in response to a change in pH or to the dilution of a chemical denaturant.  Many conformational changes occur rapidly, orders of magnitude faster than the characteristic millisecond mixing times associated with commercial fluid mixers.  Using micro/nanofabrication techniques, we produce flow cells with mixing times of microseconds.  Flexibility of design makes it possible to use these rapid mixers in conjunction with different probes of macromolecular structure, including x-ray scattering and fluorescence. 

One of our major initiatives is the use of synchrotron small angle x-ray scattering to measure the time dependence of the size and shape of macromolecules (proteins and nucleic acids) as they fold.  A key, unresolved question in protein folding is: what is the role of collapse of the denatured polypeptide chain?  Collapse is an important step in the conversion of an expanded, denatured amino acid chain into a compact, biologically active protein.  These experiments allow us to monitor both the time required for collapse as well as the size of the compact denatured or intermediate states.  Prior to our initial experiments, this information was not accessible to experimentalists on the sub-millisecond time scale! 

With this new technique, it is now possible to characterize transient states that occur during the folding process.  Information of this type is critical for comparison of experiment to untested theories of the initial events in macromolecular folding.  

 

Publications

  • R. Das, L. W. Kwok, G. S. Maskel, T. T. Mills, K. D. Finkelstein, D. Herschlag, and L. Pollack, “The counterion atmosphere surrounding DNA measured by solution x-ray scattering,” Accepted for publication in Physical Review Letters (2003).
  • R. Russell, I. S. Millet, M. W. Tate, L. W. Kwok, B. Nakatani, S. M. Gruner, S. G. J. Mochrie, V. Pande, S. Doniach, D. Herschlag, and L. Pollack. "Rapid compaction during RNA folding." Proc. Natl. Acad. Sci. USA 99, 4266-4271(2002). 
  • L. Pollack, M.W. Tate, A.C. Finnefrock, C. Kalidas, S. Trotter, N. C. Darnton, L. Lurio, R.H. Austin, C.A. Batt, S.G.J. Mochrie. "Time-resolved collapse of a folding protein observed with small angle x-ray scattering" Phys. Rev. Lett. 86, 4962-4965 (2001).
  • L. Pollack, M.W. Tate, N.C. Darnton, J.B. Knight, S.M. Gruner, W.A. Eaton and R.H. Austin.  "Compactness of the denatured state of a fast-folding protein measured by submillisecond small angle x-ray scattering"  Proc. Natl. Acad. Sci. USA 96, 10115-10117 (1999).
  • L. Pollack, E.N. Smith, and R.C. Richardson. " Determination of the sign of the electric field gradient in indium by nuclear  resonance." J. Low Temp. Phys. 106, 93-100 (1997).
  • L. Pollack, M. Hoch, C. Jin, E.N. Smith, J.M. Parpia, D.L. Hawthorne, D.A. Geller, D.M. Lee and R.C. Richardson  "Low temperature order in the heavy Fermion CeCu6 " Phys. Rev.  B52, 15707 (1995).
  • L. Pollack, E.N. Smith and R.C. Richardson.  "Field dependence of cross relaxation in scandium" Physica B 194-196, 343 (1994).
  • L. Pollack, E.N. Smith, J.M. Parpia and R.C. Richardson.  " Novel low temperature cross relaxation in NQR" Phys. Rev. Lett. 69, 3835 (1992).
  • L. Pollack, E.N. Smith and R.C. Richardson.  "NQR Experiments on ScY allows at very low temperatures" J. Low Temp. Phys. 89, 169 (1992).

 

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