Mobility analysis of nitroxides in spin labeled protein.
EPR in conjunction with site-directed spin labeling (SDSL) is a technique to study structure and dynamics of membrane proteins. EPR provides information about the local environment of the spin label that has unpaired electrons but also can measure inter-spin label distances when two spin labels are introduced inside the protein.
EPR characterization of paramagnetic centers in cytochrome c oxidase.
Approximately 30% of all known proteins are metalloproteins. They are involved in a variety of biologically important processes such as electron transfer, drug metabolism, disease mechanisms, etc. EPR has an important role not only to study the electronic structure of metalloproteins but also to characterize their redox cofactors, binding sites, substrate reactions. For example, cytochrome c oxidase is a terminal protein in the respiratory chains from mitochondria and many bacteria. A low-spin heme, heme a, accepts electrons from a copper A (CuA) center bound to subunit II, and transfers them to a binuclear center.
Detection and study of the active site of Cu,Zn-SOD.
Many enzyme reactions involve one-electron oxidation steps with formation of paramagnetic transient state of the enzyme detectable by EPR. The paramagnetic center where the unpaired electron is located, is usually centered at a transition metal (metalloproteins) or is an amino acid derived radical. Detection and identification of the paramagnetic centers is important to understand the function of the enzymes. For example, in the native SOD1 enzyme, the active site contains one Cu(II) ion that gives a very characteristic EPR spectrum.
EPR spectrum and dipolar coupling determination of bis-TEMPO.
Correct concentration of DNP polarizing agents is crucial to the success of a DNP experiment. Samples can be pre-screened before DNP experiments using the patented SpinCount module, even in the MAS rotor. Relaxation times are critical for DNP efficiency therefore P1/2 measurements at low temperature to estimate the DNP efficiencies of new polarization agents are invaluable. Another characteristic of importance in DNP measurements is the electron-electron dipolar coupling that is easily measured from solution and frozen solution EPR spectra. Read more about DNP agents