Er049x superx microwave bridge

Measurements were performed on a Bruker ELEXYS E500 spectrometer using an ER049X SuperX microwave bridge in a Bruker SHQ0601 cavity equipped with an Oxford Instruments continuous flow cryostat and using an ITC 503 temperature controller (Oxford Instruments). The Xepr software package (Bruker) was used for data acquisition and processing of spectra.

100 µl aliquots of an apo-HydA1 protein solution (50 µM in 50 mM Tris–HCl, pH 8.0, 150 mM KCl) were mixed with 100 µl of a [2Fe]^adt solution (40 µM in 50 mM Tris–HCl, pH 8.0, 150 mM KCl), resulting in final concentrations of 25 µM protein and 20 µM [2Fe]^adt complex. The mixing was carried out inside of EPR tubes in the glovebox and the reaction mixture was either frozen immediately or incubated for a defined time period before freezing in an isopropanol cold well cooled by liquid nitrogen from the outside. After freezing, the samples were stored in liquid nitrogen until the EPR measurements. CW EPR measurements were carried out with an X-band EMX Micro EPR spectrometer (Bruker) using an ER049X SuperX microwave bridge in a Bruker SHQ0601 resonator equipped with a continuous-flow cryostat and an ITC 503 temperature controller (Oxford Instruments). The spectrometer was controlled by the Xenon software package (Bruker). Spectra were recorded with a 15 G modulation amplitude and a 100 kHz modulation frequency with 1 mW microwave power at 10 K at a microwave frequency of 9.38 GHz. Shown spectra represent the average of two magnetic field scans.

Measurements were performed on a Bruker ELEXYS E500 spectrometer using an ER049X SuperX microwave bridge in a Bruker SHQ0601 cavity equipped with an Oxford Instruments continuous flow cryostat and using an ITC 503 temperature controller (Oxford Instruments, Oxford, United Kingdom). Measurement temperatures ranged from 5 to 32 K, using liquid helium as coolant. The spectrometer was controlled by the Xepr software package (Bruker).