Physical chemistry of membrane transport proteins.
Ph.D., Syracuse University
I study the sodium pump, a membrane protein that uses energy released from the hydrolysis of ATP to move sodium out of, and potassium into, cells. At rest, this one protein accounts for about 25% of the body’s energy budget. The overall reaction cycle of this pump is well known. My research seeks to examine how the pump uses the energy from ATP hydrolysis for function; specifically, how much energy is involved in each step of the reaction cycle.
The general approach in my lab is to determine the reaction rate constants for each step of the reaction cycle, and then use standard physical and chemical methods to determine the free energies involved in each step. We use several spectroscopic techniques to examine this problem. In the past, steps in the reaction cycle have been probed with absorbance, fluorescence, and Fourier-transform infrared (FTIR) spectroscopies to examine pump.
Currently, I am studying ATP binding to the pump using fluorescence resonance energy transfer (FRET), with the aim of examining this interaction at the single-molecule level. This nanobioscience approach promises to yield a large amount of information about pump function that is unavailable using classical biophysical chemistry techniques.
HELLEN, E. H., and P. R. PRATAP. (1997) Nucleotide binding to IAF-labeled Na+/K+-ATPase measured by steady-state quenching by TNP-ADP. Biophys. Chem. 69:107-121.
PRATAP, P. R., E. H. HELLEN, A. PALIT and J. D. ROBINSON. (1997) Transient kinetics of substrate binding to Na+/K+-ATPase measured by fluorescence quenching. Biophys. Chem. 69:137-151.
HELLEN, E. H., B. C. YACONO, and P. R. PRATAP. (1998) Transient kinetics and thermodynamics of anthroylouabain binding to Na+/K+-ATPase. Biophys. Chem. 71:245-253.
PRATAP, P. R., O. DEDIU, and G. U. NIENHAUS. (2003) FTIR Study of ATP-Induced Changes in Na+/K+-ATPase from Duck Supraorbital Glands. Biophys. J.85:3707-3717.
Conceptual Physics (PHY 205)
General Physics I (PHY211)
General Physics II (PHY212)
Biophysics (BIO 543/PHY 543)