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. Author manuscript; available in PMC: 2015 Oct 1.
Published in final edited form as: Biochim Biophys Acta. 2014 Jun 23;1840(10):3058–3066. doi: 10.1016/j.bbagen.2014.06.009

Fig. 3.

Fig. 3

Electron paramagnetic resonance spectra of HmbR. EPR spectra were recorded on samples containing approximately 200 μM of HmbR in sample buffer (20 mM phosphate, pH 7.4, and Anzergent™3-14) either without imidazole (Panel A), or in the presence of 500 mM imidazole (Panel B). All data were collected using a Bruker ESP300D spectrometer equipped with an Oxford Instruments ESR-900 helium flow cryostat to maintain the temperature of the samples at 10 K. The modulation amplitude was 6.477 G with a modulation frequency of 100 kHz. The microwave frequency and power were 9.6 GHz and 5 mW, respectively. The signal at g = 4.3 is attributed to minute contamination of the protein sample by rhombic iron(III). The feature at g = 2.06 is attributed to copper contamination of the EPR cavity.