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ATKINS LAB RESEARCH PROJECTS
Cytochrome P450s and their Allosteric Properties
Cytochrome P450s (CPYs) are the main enzyme family involved in drug metabolism and
elimination (clearance). CYPs found in the liver exhibit extreme substrate
promiscuity and often demonstrate allosteric effects that contribute to complex
drug-drug interactions. Such drug interactions can significantly complicate therapy
and confound the prediction of drug clearance. Therefore, it is essential to
understand the molecular basis for these allosteric effects. We use state-of-the-art
NMR, fluorescence, and mass spectrometry to understand allosteric mechanisms of
CYPs, and thereby improve predictive models of drug metabolism, toxicity, and interaction.
Recent Cytochrome P450-related publications
Atkins Lab home page
Glutathione S-transferases
The glutathione s-transferases
(GSTs) conjugate the tripeptide
glutathione (GSH) to a wide
range of electrophilic toxins
and drugs. GSTs provide an
outstanding model for the
structure- function-dynamic
landscape that uniquely distinguishes
substrate promiscuous detoxification
enzymes from substrate-specific "traditional" enzymes.
We are engineering GST
structural variants with
different protein dynamics
to understand their role
in functional promiscuity.
This project includes
additional NMR studies,
fluorescence, calorimetry,
mass spectrometry and
x-ray crystallography
(via collaboration with
the Stenkamp research
group in the Department
of Structural Biology
(Stenkamp
web site).
We are also applying
single molecule spectroscopy
methods to identify
the unique traits of
drug metabolizing enzymes,
as they differ from
substrate-selective
enzymes.
A project related to GSTs involves the lipid peroxidation product 4-hydroxynonenal (HNE).
HNE plays a key role in many diseases associated with oxidative stress including
atherosclerosis, Alzheimer's disease, Parkinson's disease, asthma, cancer, and aging.
The major route of clearance of HNE includes GST-dependent conjugation to GSH, and we
are interested in understanding the structural basis for the ability of some GSTs, but
not all, to efficiently metabolize HNE. This project also aims to understand mechanisms
by which HNE mediates its effects, and we are using cell culture models, fluorescence
microscopy, and flow cytometry, via collaboration with the Kavanagh research group in the
Department of Environmental Health and Toxicology
(
Kavanagh web site).
Recent Glutathione S-transferase-related publications
Atkins Lab home page
P-glycoprotein
P-glycoprotein is an extremely promiscuous ATP-dependent efflux transporter that confers
cellular resistance to a wide range of drugs and toxins. Just as promiscuous enzymes
must recognize and metabolize many structurally unrelated substrates, P-glycoprotein
couples ATP hydrolysis to the pumping of an amazingly wide range of molecules and
it plays a major role in drug resistance, toxicity, and drug-drug interactions. We
employ a wide range of biophysical and spectroscopic methods to understand the
conformational coupling that controls the ATP-dependent extrusion of these
drugs and toxins.
Recent P-glycoprotein-related publications
Atkins Lab home page
Phospholipid Bilayer Nanodiscs
Tools for Studying Membranes and Membrane Proteins
Phospholipid bilayer Nanodiscs are novel membrane models that are potentially useful in
the study of small-molecule binding to membranes and membrane proteins. Nanodiscs
consist of a protein coat wrapped around a lipid bilayer about 10 nm across. Because
their size is constrained by the presence of the protein coat, Nanodiscs display much
more consistent and monodisperse particle size distributions than conventional
model membranes.
We are using Nanodiscs
to study the thermodynamics
and kinetics of small-molecule
binding to membranes
using steady-state and
stopped-flow fluorescence
and absorbance spectroscopy,
as well as surface plasmon
resonance. CYP3A4 and
P-glycoprotein can be
incorporated into Nanodiscs,
and can thereby be maintained
monomerically at high
enzyme concentrations.
We are using the Nanodisc
complexes to investigate
the effect of model membranes
on small-molecule binding
to these membrane proteins,
with particular regard
to the competition for
ligand binding between
the active site of the
protein and the membrane
phase.
Recent Nanodisc publications
Atkins Lab home page
Therapeutic Antibodies
A new area of research for
our group includes therapeutic
antibodies and antibody-drug
conjugates. These represent
a therapeutic platform
with rapidly growing importance.
Although antibody drug
conjugates have enormous
potential as therapeutics,
much basic research is still
needed to understand how
the nature of the chemical
structure of the linker and
conjugate, and the antibody
isotope, affects the therapeutic
properties. The relationships
between these molecular properties
and the biological properties
associated with clearance,
tissue distribution,
cellular uptake and efficacy
are not established.
Recent Antibody publications
Atkins Lab home page
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