Ka Yee Lee Group
 Professor
 Postdoctoral Scholar
 Graduate Students
Ka Yee C. Lee
kayeelee @ uchicago.edu        Office: GCIS 139B    Phone: 773-702-7068
 
Department of Chemistry, James Franck Institute, Materials Research Science and Engineering Center,
Institute for Biophysical Dynamics, The University of Chicago
 
 
Ph.D. Harvard University, Cambridge, MA
B.S. Brown University, Providence, RI
 
Kathleen Cao
kcao @ uchicago.edu
 
Ph.D. University of Chicago, Chicago, IL
B.S. University of California, Irvine, CA
I am interested in the fundamental molecular interactions between cholesterol and phospholipids by using model lipid  membranes. The cell membrane is believed to be laterally heterogeneous due to the presence of ordered nanodomains enriched in cholesterol called lipid rafts. The role and importance of lipids rafts in cellular functions, such as signaling, trafficking, and protein attachment, are widely known and accepted, but their formation and the interactions involved in their assembly have yet to be determined.  I am investigating if there is a propensity for these molecules to form complexes with characteristics distinct from the original lipid components and the chemical activity states of cholesterol.
 
 Research Technician
 
 
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Michael Henderson
jhenderson @ uchicago.edu
 
 
 
Charles Heffern
heffern @ uchicago.edu
 
B.S. University of Southern California, Los Angeles, CA
My research involves studying the interactions between antimicrobial peptides and lipid membranes.  Largely distributed among living organisms, antimicrobial peptides (AMPs) are a class of small (<100 amino acid residues) host defense peptides that induce selective membrane lytic activity against microbial pathogens.  The permeabilizing behavior of these peptides has been exclusively applied to the formation of well-defined pores; however, recent findings suggest that pore formation is a small part of a much more complex phase diagram applicable to that of a detergent-like mechanism.  Within a detergent-like mechanism, the intercalation of these peptides into the bilayer results in a variety of aggregate structures beyond that of lamellar bilayers.  Using atomic force microscopy, concentration dependent morphological transformations of model lipid membranes are visualized.  By studying a selection of structurally different AMPs, I hope to gain an understanding about the universality of antimicrobial peptides as biological detergents. 
 
Zhiliang Gong
zlgong @ uchicago.edu
 
B.S. University of Science and Technology of China, Hefei, Anhui, P.R. China
My research interests include the role of phospholipids in diverse biological processes involving proper respiratory function. Phospholipids are the primary component of lung surfactant (LS), a complex mixture at the air-alveolar lining fluid interface that is responsible for reducing the interfacial surface tension, without which proper function is not possible. Disorders such s acute respiratory distress syndrome (ARDS) and neonatal respiratory distress syndrome (NRDS) are known to be caused by disruption of the LS. I study the conditions necessary to create a simple, synthetic mixture that reproduces the mechanical properties of natural LS and can be used to replace LS in these disorders. Phospholipids have also been implicated as paracrine signaling molecules that induce the onset and resolution of ARDS. I am interested in studying the function of phospholipids as signaling molecules in the progression of ARDS, and how this signaling can be utilized in its treatment.
 
Antibiotic resistance is a growing global concern. A promising class of innate immune system molecules known as antimicrobial peptides (AMPs) may be a model for the next generation of antibiotic therapeautics. It is necessary to study AMPs from a variety of perspectives in order to acquire as complete an understanding of their activities as possible. I study the effects of cholesterol (Chol), an important physiological modulator of membrane fluidity, on the binding of AMP protegrin-1 (PG-1) to phospholipid model membranes. I use a powerful technique known as isothermal titration calorimetry (ITC) to quantify the effects of Chol-mediated variations in membrane fluidity on the thermodynamics of interaction between PG-1 and phospholipid model membranes.
 
I’m interested in the clustering of phosphatidylserine (PS) and its interaction with proteins. PS is the most abundant negatively charged lipid in cell membranes, constituting 10-20% of cell lipids, and plays a vital role in numerous cellular functions, including blood coagulation, cell fusion, and clearance of apoptotic cells via biding to various proteins. Around 30 PS-binding proteins have been identified. How these proteins recognize such a ubiquitous signal to initiate distinct cellular cascades, however, is unclear. There is the possibility that different PS-binding proteins are sensitivity to the local distribution of PS. Existing evidence supports PS clustering into microdomains of around 10-100 molecules, but the picture is rather fragmental. By use of fluorescence spectroscopy, FRET, NMR, and some canonical proteins, I hope to clearly establish PS clustering, its dependence on various factors, and its interaction with different proteins.
 
Luke Hwang
hhwang04 @ uchicago.edu
 
B.S. City College of New York, New York, NY
Research Interest: I am broadly interested in lipid-polymer interactions in the context of facilitated membrane repair and controlled permeation for pharmaceutical purposes. I examine the details of two-state interaction — surface adsorption and bilayer insertion — of polymers with various model membranes. Currently, with giant unilamellar vesicles of varying composition, I am studying how amphiphilic block copolymers belonging to Pluronic® and Tetronic® families can help reseal membrane under osmotic and oxidative stress. My overall objective is to elucidate the lipid and polymer structural parameters that govern the degree of their interaction by using a host of sensitive thermodynamic, fluorescence, and scattering techniques
 
Daniel Kerr
danielhskerr @ uchicago.edu
 
B.S. University of California, Santa Barbara, CA
 Undergraduate Student
 
Andrew Molina
avmolina @ uchicago.edu
 
 
My current research interests center around the biophysical process of nanotubule self-assembly associated with Central Nervous System (CNS) myelinogenesis. The myelin sheath is a layer of insulation consisting of a mixture of proteins and lipids that surrounds the axons of neurons and allows for the rapid transmission of electrical impulses throughout the body. This functionality is disrupted by demyelinating diseases such as multiple sclerosis, in which the myelin sheath breaks down and the propagation of the electrical impulse is significantly compromised. Specifically, I study the role of phospholipids, glycolipids, cholesterol, galactocerebrosides, sulfatides, and myelin-specific proteins in forming tubular myelin structures recently observed around developing CNS myelin sheaths. I aim to find the optimal conditions and ratios of myelin constituents for spontaneous tubule self-assembly in attempts to recreate in vitro the observed tubules.  In the future, I hope to study the conditions and driving forces behind these tubules’ transition into multilamellar structures characteristic of a mature myelin sheath. Ultimately I intend for my research to advance the current understanding of CNS myelin sheath formation.
 
 Visiting Summer Students
 
Kit Sang (Simon) Chu
s1155033656 @ link.cuhk.edu.hk
 
 
TIM is a family of immunological proteins. Three of them, TIM-1, TIM-3 and TIM-4 are known to be present in human. Although they all recognize the lipid, phosphatidylserine, different expression and function correspond to each of the proteins due to their unique molecular structures. I aim to refine an x-ray reflectivity protocol in order to determine the most probable protein structure at the membrane-protein interface. In my project, TIM-3 is studied with the aid of computational molecular dynamics to identify its structure under the interactions with a membrane.
 
Tiffany Suwatthee
 
 
I am researching the thermodynamic interactions between antimicrobial peptides and lipid membranes. Antimicrobial peptides are a class of small host defense peptides that induce selective membrane lytic activity against microbial pathogens. By looking at their binding isotherms between lipids with different concentrations of cholesterol, I hope to help determine if these different compositions are the reason antimicrobial peptides concentrate their attacks on bacterial cells rather than mammalian cells.
 
Structures of proteins in their functional contexts are difficult to ascertain using current structural determination methods. For proteins that interact with lipid membranes, x-ray scattering techniques can help characterize their dynamic structure in thermodynamic conditions which model physiological conditions. Extracting this information from x-ray scattering techniques is not trivial, I work on the modeling and analysis techniques of x-ray scattering to better predict the structure of proteins in complex with lipid membrane. Using molecular dynamics to generate possible structures, I use the x-ray data to determine which structures are most likely. My work is focused on the TIM family of proteins, which all recognize phosphatidylserine but respond differently possibly due to the differences in their structures in complex with lipid membranes.
 
Nishanth Iyengar
nishanth2015 @ uchicago.edu
 
B.S. The University of Chicago, Chicago, IL