Serum Albumin: Binding and Transport of Pharmaceuticals and Functional Differences Derived from Divergent Evolution Characterized by Electron Paramagnetic Resonance (EPR) Spectroscopy

• Applicant: Professor Dr. Dariush Hinderberger
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 257288979

Building on an EPR (electron paramagnetic resonance)-based research platform recently developed for the study of serum albumins, this proposal has two major objectives that are interconnected. The first goal is to understand structural plasticity and dynamics of serum albumin (human and animal, e.g. bovine) when binding small pharmaceutically active molecules and when interacting with a membrane. This will be achieved using EPR spectroscopy and will help bridging the gap between fundamental structural biology-related research on albumin and its medical implications. Nine different pharmacologically important classes of drugs have been identified beforehand that shall be studied in this part of the project. These classes are: 1) Analgetics (drugs for pain relief), 2) Anticoagulants; 3) Narcotics; 4) Uricostatics (prevention of kidney stones); 5) Uricosurics (gout medication); 6) Cytostatics; 7) Steroids (hormones); 8) Vitamins; 9) Antiauxins. The binding of these spin-labeled drugs to albumin by EPR spectroscopy and other physical techniques (e.g. isothermal titration calorimetry, ITC) is then characterized. Furthermore, changes in plasticity of albumins (human) as derived from pulse EPR (DEER) measurements when ligands are bound are characterized. This includes understanding allosteric effects of concurrent binding of drugs and fatty acids. Then the study aims at exploring interactions of (drug-, fatty-acid-)loaded (human, bovine) albumins with artificial membranes and the ensuing changes in structure/plasticity of the protein. This will be achieved by a combination of EPR spectroscopic methods and surface-sensitive infrared reflection-absorption spectroscopy (IRRAS). The second big aim of this proposal is to understand the structure-function relationship of six different mammal albumins and how differences in structure, plasticity and function of albumins (human and animal) may have arisen. This part thus aims at connecting the evolution of albumins with the difference in solution structural plasticity. The proposal hence is to 'follow evolution with EPR': Use the EPR-spectroscopic research platform for characterizing albumin solution structure to find out where in the divergent evolution from a common mammal ancestor the plasticity of albumin surface (as seen in HSA) has emerged. Then it is studied how much sequence identity with HSA is necessary to display this plasticity and which amino acids, mostly on the surface of the proteins, are important to switch from static (BSA) to plastic (HSA). Moving from this point, it is then characterized how differences in plasticity translate into functional differences, e.g. in uptake, release or transport of ligands. Finally, it is investigated how posttranslational modification of albumins alters the structure-function relationship.

• DFG Programme: Research Grants