title: Experimental system for real-time assessment of potential changes in protein conformation induced by electromagnetic fields.
abstract: A novel experimental system to distinguish between potential thermal and non-thermal effects of electromagnetic fields (EMFs) on the conformational equilibrium and folding kinetics of proteins is presented. The system comprises an exposure chamber installed within the measurement compartment of a spectropolarimeter and allows real-time observation of the circular dichroism (CD) signal of the protein during EMF exposure. An optical temperature probe monitors the temperature of the protein solution at the site of irradiation. The electromagnetic, thermal, and fluid-dynamic behavior of the system is characterized by numerical and experimental means. The number of repeated EMF on/off cycles needed for achieving a certain detection limit is determined on the basis of the experimentally assessed precision of the CD measurements. The isolated thermosensor protein GrpE of the Hsp70 chaperone system of Eschericha coli serves as the test protein. Long-term experiments show high thermal reproducibility as well as thermal stability of the experimental setup.
authors: Laboratory for Electromagnetic Fields and Microwave Electronics, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.
authors: Christian
authors: C
authors: Beyer
authors: Philipp
authors: P
authors: Christen
authors: Ilian
authors: I
authors: Jelesarov
authors: Jürg
authors: J
authors: Fröhlich
mesh_terms: D002942:Circular Dichroism; D004563:Electrochemistry / Q000295:instrumentation; D004574:Electromagnetic Fields; D029968:Escherichia coli Proteins / Q000528:radiation effects; D006360:Heat-Shock Proteins / Q000528:radiation effects; D011487:Protein Conformation / Q000528:radiation effects*; D011840:Radiation, Nonionizing; D015203:Reproducibility of Results; D062125:Thermometry / Q000295:instrumentation
chemical_list: D029968:Escherichia coli Proteins; C489400:GrpE protein, E coli; D006360:Heat-Shock Proteins
keywords: circular dichroism; electromagnetic fields; non-ionising radiation; protein conformation; protein folding kinetics; real-time assessment; spectropolarimetry