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biochemistry and biophysics


Professor of Biochemistry and Biophysics

260 Anatomy-Chemistry Building
(215) 898-6917

M.D. Johns Hopkins (1958)



Dr. Liebman's laboratory uses physical biochemical approaches to determine the mechanisms that control strength, speed and stability of signaling molecule interactions in hormone, neural and sensory signaling systems with emphasis on receptors, G proteins and membranes. The 7-transmembrane helix receptor (7TMHR) family initiates cell signaling events for thousands of hormones, pheromones and neuro-transmitters plus light, taste and smell stimuli. Each receptor requires a G protein signaling partner.

With a view to understand the molecular mechanics of all such systems, current work of Dr. Liebman's laboratory focuses on the most accessible of these systems, and studies: 1) the molecular coupling mechanism of visual transduction; 2) the mechanism of nucleotide activation of G proteins; 3) G protein ligand-dependent folding stability; 4) 7TMHR conformation, kinetics and stability; 5) the structural basis for receptor-arrestin and G protein recognition and effect of receptor phosphorylation; 6) the role of membrane protein embedding and surface charge in the above; and 7) the mechanism of anesthetic effect on signaling proteins. Specific thermodynamic, kinetic and structure questions and models are investigated through experiments utilizing computational modeling, UV-visible absorption, circular dichroism and tryptophan fluorescence spectroscopy, light scattering, calorimetry and radiotracers which are interpreted in light of static x-ray and NMR structures of the respective native proteins and activity of their misfunctional mutants.

Dr. Liebman is the originator and director of Biochem/Biophys 550, Molecular mechanisms of signal transduction and control.

2015 The Trustees of the University of Pennsylvania