116 / 161
Conformational Ensembles from Experimental Data
and Computer Simulations
Poster Abstracts
112
77-POS
Board 37
Unfolding Pathway of Human Serum Albumin Studied by Isothermal Chemical
Denaturation and Molecular Dynamics Simulations
Rikke L. Knudsen, Alina Kulakova, Sowmya Indrakumar, Pernille Harris, Jens T. Bukrinski,
Günther H. Peters
.
Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
Protein aggregation is one of the grand problems of biophysics. It is highly complex, sensitive to
initial conditions, operates on a wide range of timescales and its products range from dimeric
proteins to macroscopic fibrils. Unwanted aggregation, for instance, has implications in
biotechnology, where protein aggregation leads to reduced yield in bioprocessing, and human
health, where aggregation-based diseases such as Alzheimer, Parkinson, and Huntington affect
millions of people. Hence, an understanding of the molecular mechanisms underlying protein
aggregation is of great relevance in diverse research fields such as medicine, pharmacy, food
science and industrial biotechnology. The challenge is when proteins are exposed to conditions
that are far from physiological conditions and where stability and solubility become critical. The
aim of the current study is to gain better fundamental understanding of the relation between
protein properties and their role in protein aggregation propensity, and to explore on a molecular
level how solution conditions (e.g. pH) affect protein stability. We have chosen human serum
albumin as a model system to study the pH-induced unfolding of the protein applying isothermal
chemical denaturation (ICD) and classical molecular dynamics simulations. ICD measurements
are performed at different pHs and concentrations of the denaturing agents urea and guanidine
hydrochloride. The study was supplemented by classical molecular dynamics simulations
performed at different pHs to provide a molecular understanding of the unfolding pathway and to
identify specific regions in the proteins that act as hotspots driving protein instability and hence
protein aggregation.